iPlumb.tv offers copper crimp rings for both PEX and Polybutylene (PB) tubing. The copper rings are pure annealed copper and color coded for easy identification. The rings for PEX tubing are either solid black or copper colored with black “PEX” clearly on the side, while the rings for PB tubing are solid copper colored. The PEX rings meet ASTM F1807 and ASTM F2159 specifications. The PB rings meet ASTM F1380 specifications.