1.1 ,This specification covers polyethylene (PE 4710) electrofusion fittings for use with outside diameter-controlled crosslinked polyethylene (PEX) pipe, covered by Specifications F2788/F2788M, F2905/F2905M and F2968/F2968M. As stated in these PEX pipe standards, the PEX pipes joined to these PE 4710 electrofusion fittings have an HDB of 1250 psi or 1600 psi at 73 ,°,F (23 ,°,C) per Test Method D2837.