1.1 This specification establishes requirements for sulfone plastic insert fittings and copper crimp rings, or alternate stainless steel clamps for four sizes Nominal Tubing Sizes (NTS) (³/₈ , ¹/₂ , ³/₄ , and 1) of cross-linked polyethylene (PEX) tubing that meet the requirements for Specification F876 or Specification F3253, or polyethylene of raised temperature (PE-RT) tubing that meet the requirements of Specification F2623 or Specification F2769. These fittings are intended for use in 100 psi (690 kPa) cold- and hot-water distribution systems operating at temperatures up to and including 180 °F (82 °C). Included are the requirements for material, molded part properties, performance, workmanship, dimensions, and markings to be used on the fittings and rings.