AMBD-6300,

This 4 to 6 inch first check poppet assembly can be used on the Deringer 40(X) and 50(X) models. They are designed for sizes and come pre-assembled from the factory ready for installation. The True Seal(TM) check valve was designed to incorporate a poppet only motion during the check stroke and is used exclusively on the first check assembly on the Deringer RP and RPDA models. This design allows a more consistent pressure loss across the check valve which helps maintain a steady and continual closure of the relief valve.