Cresline HD polyethylene flexible pipe is produced using virgin PE 4710 high density polyethylene (HDPE) to meet or exceed ASTM D2239 and ASTM 2737 standards and is NSF-approved for drinking water use. HD is black in color and is available in both Iron Pipe Size (IPS) and Copper Tube Size (CTS). Unique and functional footage markings help you get the most out of every purchase.