The 2 1/2 - 10" Febco 805 Series double check assemblies began production in 1973 and is still currently in production. The body is constructed of epoxy coated cast iron. The 805/805Y (1973-88) model 2 1/2 - 3" featured bronze check assemblies and the 4 - 10" where epoxy coated cast iron. 2 1/2 - 3" checks do not have contained springs while the 4 - 10" check designs are self contained and require a spring compression tool to change springs. No special tools needed to replace rubbers. Very early models contained aluminum check assemblies which were prone to erosion damage. The check seats were removable on the 805Y although a special seat removal tool was needed. In 1988 the 805YD was introduced. The body was changed to a ductile iron, painted epoxy coating. In 1991, the painted epoxy coating was replaced with a fused epoxy coating. All check assemblies where changes to stainless steel construction. The newer stainless steel checks are interchangable with the older cast iron or bronze check assemblies. The seats were redesigned so no special tools are required for servicing. The covers were also redesigned and in turn the cover O-rings are different. All rubber repair kits include both old and new style cover O-rings. Check disc rubbers remained the same through all the years of changes.