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As one of the leading suppliers of plastic pipe systems, Uponor attaches great importance to product development. Uponor ProPEX rings are made of crosslinked polyethylene PEX-a material. The ½ inch through 3 inch rings include a leading-edge chamfer on one side of the ring and a stop edge on the other side. Use Uponor ProPEX rings to make proper ProPEX ASTM F1960 expansion connections in PEX-a piping systems. The leading-edge chamfer on the ½ inch through 3 inch rings makes it easy to slide a ring onto Uponor PEX-a pipe. The integral stop edge ensures the required 1/16 inch overhang over the edge of the pipe, which keeps the ring from sliding down the pipe during the expansion process. The product consists of the following materials more than 99% polypropylene and less than 1% additives. Crosslinked polyethylene PEX manufactured using the PEX-a Midas method.