The 8" Febco 856 Series double check detector assemblies began production in 1993 and was discontinued in 2014. The 856 was replaced by the 856ST which is the lead free version to meet new nation wide codes. Known as the "Master Series" the 856 is constructed of epoxy coated ductile iron with bronze check assemblies. Checks are a swing check type with self contained spring modules. Check seats are replaceable. Check discs are vulcanized rubber disc type. Bypass assembiy shall be either 3/4" Febco 805Y or 3/4" 805YB. No special tools are required for servicing.