1.1 This specification covers metal insert fittings and copper crimp rings for use with cross-linked polyethylene (PEX) tubing in 3/8 , 1/2 , 5/8 , 3/4 , 1, 1 1/4 , 11/2 , and 2 in. nominal diameters that meet the requirements for Specification F876 and for use with polyethylene of raised temperature (PE-RT) tubing in 3/8 , 1/2 , 5/8 , 3/4 and 1 in. and 1 1/4 in. nominal diameters that meet the requirements of Specifications F2623 and F2769. These fittings are intended for use in 100 psi (689.5 kPa) cold- and hot-water distribution systems operating at temperatures up to, and including, 180°F (82°C). The requirements for materials, workmanship, dimensions, and markings to be used on the fittings and rings are also included.