The 2" Wilkins 950XL Double Check Valve Assembly was designed to replace the original 950 and 950A models. The difference in the 950XL was the plastic replacable seats. The 950XL is a two cover, wye pattern design. The checks are a poppet style and are not self contained and there is spring pressure against the covers. The body is of bronze construction. A seat removal tool is required for seat service.