The 1 1/4" Wilkins Model 350XL double check assemblies began production in 2010 and are currently still being produced. The 350XL is the lead free version of the model 350. They feature a lead free bronze carriage that holds a plastic body which houses the check assemblies. The plastic housing rests into the bronze carriage and is locked in with a wedge system. The device is an inline module check design. No special tools are required for servicing.