Inch Pipe
machanism of pipe extrusion line
In addition to the pressure rating and standards set forth to accomplish this end, specific plastics require different dies in the formation of the pipe. For example, a plastic, such as polyethylene, which has an appreciable amount of memory, requires a die having an elongated heated section, which actually is the main pipe forming section of the die. This section of the die is also referred to as the “land” and its length as the “land length”, and is an elongated, substantially straight annular space formed between an elongated outside bushing ring and an elongated inside mandrel. In order to produce a given size pipe meeting the specifications for a given SDR, experience with the use of a given plastic teaches one that a die should have a land length to die opening ratio of approximately a predetermined value, where the die opening is the thickness of the annular space between the outer bushing and the inner mandrel. For example, for a particular polyethylene, it has been found that a land length to die opening ratio of approximately 35:1 must be met for efficient extrusion and the production of pipe meeting standard specifications.
It is also obvious that, in the pipe extrusion line of large diameter pipe, the cost as well as the handling of heavy metal dies, particularly those having long land lengths, becomes a serious problem. This problem is aggravated by the fact that a given diameter pipe, having a given SDR value, requires a specific die opening and thus each die can be used only for making a single diameter pipe having a single SDR. As indicated, for large diameter pipes, this becomes a real problem because of the cost of such dies. As a result, such dies, for producing large diameter pipes, are often shipped from one manufacturing plant to another of the same owner, rather than to purchase more than one die for each size pipe having a particular SDR rating. Another cost saving procedure, followed by some pipe manufacturers, to overcome this problem is to have a die built for a single pipe diameter and a plurality of inside bushings which can be substituted for one another each time a different die opening is desired to produce pipe of that particular outside diameter but having different SDR ratings. As previously indicated, the internal mandrel is a heavy metal elongated ring. Removal and replacement of the inner mandrel is not a serious problem with small diameter pipes below about 6 inches, since the mandrel will have an outside diameter less than 6 inches and a length less than about 27 inches. However, for larger extrusion dies, such as those for the production of 18 -inch and 24-inch pipe, a serious problem exists since the mandrel will be nearly 18 or 24 inches in diameter and as long as 98 inches and up.
In practice of the previously mentioned procedure of removing and replacing the entire mandrel, for example, utilizing a set of three mandrels for making 24-inch pipe having SDR ratings of 32.5, 21 and 11, respectively, the die is designed for a mandrel for the thinnest pipe (SDR 32.5) and replacement mandrels of the same length are supplied for the heavier walls required for SDR 21 and SDR 11 pipes. The result of this design is that a 24-inch die designed for extrusion of a plastic requiring a 35:1 land length to die opening ratio (for an SDR 32.5) will result in the modified die for producing SDR 21 pipe having an effective land length to die opening ratio of 22:1 and the modified die for making SDR 11 pipe having an effective land length to die opening ratio of 12:1. Obviously, the large variations from the required land length to die opening ratio of 35:1 can create very serious problems, both in the formation of the pipe extrusion line by the die, as well as the production of pipe meeting the various standards and specifications.
It is, therefore, an object of the present invention to provide an improved die assembly for the pipe extrusion line of thermoplastic pipe. Another object is to provide an improved die assembly for the extrusion of thermoplastic pipe, wherein a single basic die can be converted for the production of a specific diameter pipe having different SDR ratings. Another and further object of the present invention is to provide an improved die assembly for the extrusion of thermoplastic pipe from a plastic exhibiting an appreciable amount of memory. A still further object of the present invention is to provide an improved die assembly for the extrusion of thermoplastic pipe which is adapted to produce a given diameter pipe having a plurality of different SDR ratings, which die closely approximates a predetermined land length to die opening ratio for each of the different SDR ratings. Yet another object of the present invention is to provide an improved die assembly for the extrusion of thermoplastic pipe which is capable of being converted to the production of pipe of a given diameter but having different SDR ratings by replacement of a single relatively small element with a minimum of part removal and replacement. Another further object of the present invention is to provide such an improved die assembly which can be converted for use with plastics having different degrees of shrinkage.
About the Author
It is also obvious that, in the pipe extrusion line of large diameter pipe, the cost as well as the handling of heavy metal dies, particularly those having long land lengths, becomes a serious problem. This problem is aggravated by the fact that a given diameter pipe, having a given SDR value, requires a specific die opening and thus each die can be used only for making a single diameter pipe having a single SDR
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Carey ‘Magic Inch’ Pipe $0.01 |
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Ridgid Rigid Threading Head Model 141 Pipe Threader 2 1/2-4 Inch Jam Proof NR $0.01 |
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Bronze Skin Fitting 2 inch with ball valve and angle pipe fitting $0.99 |
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.99 PER DOZEN Premium 3/4 inch Brass Screens for Tobacco Pipes.QUALITY SCREENS $0.99 |
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1 1/2 Inch Pipe Stem Triangle QTY 2 $0.99 |
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ORBIT- PVC PIPE CUTTERS 1 INCH $0.99 |
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2 estate Tobacco PIPES Carey Magic Inch & Frank Medico — Mediterranean Briar $0.99 |
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5 NEW J HOOKS FOR PVC PIPE 2-4 INCH AND 3-3INCH $0.99 |
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JVI Water Pipe Ground Clamp – 1/2″ inch to 1 1/4″ inch $0.99 |
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4 LOT – JVI Water Pipe Ground Clamp – 1/2″ inch to 1 1/4″ inch $0.99 |
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Primitive Folk Art Hand Carved Wooden Peace Pipe Childs Toy Just Over 21 Inches $0.99 |
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VINTAGE MAGIC INCH BY CAREY ESTATE PIPE $0.99 |
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1ct. Brand New ORIGINAL Straight Stem Corn Cob Pipe 5.5 inch long corn pipe $0.99 |
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1″ PIPE LOCKNUT FOR 1 INCH PIPE STYLE MUFFLER 897 $1.00 |
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3/4″ .75″ inch HW Conduit Pipe Strap Clip Fastener Holder $1.00 |
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1 1″ inch TW Conduit Pipe Clip Strap Fastener Holder $1.00 |
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1 HW 1″ inch Conduit Pipe Clip Strap Fastener Holder $1.00 |
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3/4 HW .75″ inch Conduit Pipe Strap Clip Fastener Holder $1.00 |
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BridgePort Fittings .5″ inch 1/2 EMT ET Conduit Pipe Strap Clip Fastener Holder $1.00 |
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JACO 1/4 inch Pipe Nipple $1.00 |
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Genova 1 1/2 Inch Poly Female Pipe Thread Insert Elbow $1.18 |
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3mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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3mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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3mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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3mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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6mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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6mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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6mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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6mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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6mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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6mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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6mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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6mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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6mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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6mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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6mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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6mm x 12 inch CHENILLE PIPE CLEANER STEMS 25pc $1.19 |
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25 Quality GOLD 1/2 INCH PIPE SCREENS FILTERS $1.25 |
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25 SILVER 3/4 INCH PIPE SCREENS $1.25 |
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SCARCE INDIAN WAR ERA SOLDIERS 7 INCH CLAY PIPE, WOOD STEM – HORN MOUTHPIECE $1.26 |
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8mm x 12 inch TWISTED TINSEL PIPE CLEANER STEMS 10 pc $1.49 |
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8mm x 12 inch TWISTED TINSEL PIPE CLEANER STEMS 10 pc $1.49 |
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8mm x 12 inch TWISTED TINSEL PIPE CLEANER STEMS 10 pc $1.49 |
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Dill’s Bristle Premium Pipe Cleaners NEW 32 Ct 6 inches $1.49 |
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1/2 Inch I.D. Ultra-Flex PVC Pipe Tubing/ ft $1.49 |
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Polished Chrome 3/4 Inch Shower Head Pipe in original wrapping $1.50 |
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small ebony black carve wood pipe 3 inch tiny little smoking herb tobacco herbal $1.56 |
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JCS Worm Drive Hose Clips HiGrip Clamps Radiatior Air Water Fuel Silicone Pipe $1.56 |
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4mm ID Silicone Vacuum Hose Tubing Dump Radiator Coolant Rubber Vac Pipe Silicon $1.56 |
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4mm ID Silicone Vacuum Hose Tubing Dump Radiator Coolant Rubber Vac Pipe Silicon $1.56 |
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4mm ID Silicone Vacuum Hose Tubing Dump Radiator Coolant Rubber Vac Pipe Silicon $1.56 |
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4mm ID Silicone Vacuum Hose Turbo Dump Radiator Rubber Air Vac Pipe Silicon Tube $1.56 |
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4mm ID Silicone Vacuum Hose Turbo Dump Radiator Rubber Air Vac Pipe Silicon Tube $1.56 |
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4mm ID Silicone Vacuum Hose Turbo Dump Radiator Rubber Air Vac Pipe Silicon Tube $1.56 |
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Paul McCartney PIPES OF PEACE / SO BAD 7″ INCH Single Vinyl 45 RPM Record $1.56 |
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Pipe Thread Seal Tape – 1/2 inch x 520 Inch Roll $1.59 |
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6mm x 12 inch TINSEL PIPE CLEANER STEMS 25pc $1.69 |
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6mm x 12 inch TINSEL PIPE CLEANER STEMS 25pc $1.69 |
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6mm x 12 inch TINSEL PIPE CLEANER STEMS 25pc $1.69 |
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6mm x 12 inch TINSEL PIPE CLEANER STEMS 25pc $1.69 |
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NEW COPPER PIPE 1 1/2″ TYPE L HARD DRAWN BY THE INCH NEVER USED / CUSTOM FOOTAGE $1.69 |
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3/4 Inch I.D. Ultra-Flex PVC Pipe Tubing/ ft $1.69 |
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3mm x 12 inch TINSEL PIPE CLEANER STEMS 35 pc $1.69 |
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3mm x 12 inch TINSEL PIPE CLEANER STEMS 35 pc $1.69 |
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3mm x 12 inch TINSEL PIPE CLEANER STEMS 35 pc $1.69 |
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3mm x 12 inch TINSEL PIPE CLEANER STEMS 35 pc $1.69 |
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2 U Bolts 5/16 x 2 1/2 wide x 3 1/4 tall – 2 Inch Pipe $1.75 |
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New Classic Durable Corn Cob Tobacco Smoking Pipe 3 1/2 inch Amber straight stem $1.75 |
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Automec Brake Pipe Chassic Clip – Triple For 3/16″ Inch Pipe – Each $1.87 |
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NEW 2 1/2″ COPPER PIPE * TYPE L* HARD DRAWN* BY THE INCH* CUSTOM SIZES $1.89 |
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1/8 NPT close brass pipe nipple fitting 3/4 inch long $1.89 |
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NEW 1 1/2″ COPPER PIPE * TYPE L* HARD DRAWN* BY THE INCH* CUSTOM SIZES $1.89 |
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Four Seasons Heater Fitting Square Head Pipe Plug 1/4 inch Male Pipe Thread Ea $1.95 |
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RIDGID 14 INCH PIPE WRENCH IN GREAT WORKING CONDITION PAINT HAS ALMOST WORE OFF $1.99 |
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6mm x 12 inch TINSEL PIPE CLEANER STEMS 25pc $1.99 |
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6mm x 12 inch TINSEL PIPE CLEANER STEMS 25pc $1.99 |
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NEW OLD STOCK 2 1/2″ COPPER PIPE TUBE BY-THE-INCH $1.99 |
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1ct. Brand New ORIGINAL Curved Stem Corn Cob Pipe 5.5 inch original corn pipe $1.99 |
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1/4″ inch NPT Pipe Plug Anodized Red Fuel Fitting REDHORSE PERFORMANCE 2 pc NEW! $1.99 |
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1 Inch I.D. Ultra-Flex PVC Pipe Tubing/ ft $1.99 |
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Streamline 2″ Copper Pipe-Type L-Hard Drawn-Custom Sizes-By the Inch-Mueller Ind $2.00 |
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Malleable Galvanized Cross Pipe Fitting 1 1/2 inch BUY IT NOW FOR $4.99! $2.00 |
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JCS Worm Drive Hose Clips HiGrip Clamps Radiatior Air Water Fuel Silicone Pipe $2.04 |
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JCS Worm Drive Hose Clips HiGrip Clamps Radiatior Air Water Fuel Silicone Pipe $2.09 |
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1 inch or 1/2 inch bone hair pipe beads, hairpipe, YOU GET 25pcs…. LOT OF 25.. $2.10 |
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HERRINGBONE OIL PIPE PER INCH 5/16 ID 9/16 OD $2.12 |
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NEW 2″ COPPER PIPE * TYPE L* HARD DRAWN* BY THE INCH* CUSTOM SIZES $2.15 |
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JCS Worm Drive Hose Clips HiGrip Clamps Radiatior Air Water Fuel Silicone Pipe $2.20 |
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JCS Worm Drive Hose Clips HiGrip Clamps Radiatior Air Water Fuel Silicone Pipe $2.23 |
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VERY NICE CAREY MAGIC INCH SMOKING TOBACCO PIPE VINTAGE? $2.25 |
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NEW COPPER PIPE 2″ TYPE L HARD DRAWN BY THE INCH NEVER USED / CUSTOM FOOTAGE $2.25 |
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JCS Worm Drive Hose Clips HiGrip Clamps Radiatior Air Water Fuel Silicone Pipe $2.28 |
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48 BRISTLE PIPE CLEANERS 6 INCH BUY 2 OR MORE & SAVE $2.29 |
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JCS Worm Drive Hose Clips HiGrip Clamps Radiatior Air Water Fuel Silicone Pipe $2.34 |
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JCS Worm Drive Hose Clips HiGrip Clamps Radiatior Air Water Fuel Silicone Pipe $2.39 |
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JCS Worm Drive Hose Clips HiGrip Clamps Radiatior Air Water Fuel Silicone Pipe $2.44 |
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Darice Chenille Stems (Pipe Cleaners) 12 inch 100 pcs Neons NEW $2.49 |
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Fiber Craft Chenille Stems (Pipe Cleaners) 12 inch 100 pcs Light Blue NEW $2.49 |
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JCS Worm Drive Hose Clips HiGrip Clamps Radiatior Air Water Fuel Silicone Pipe $2.55 |
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2 1/2 Inch Type L Copper Pipe – By the Inch !!! $2.55 |
