Bendix 5004910 is a maintenance kit for the R-12DC, a genuine Bendix part from Pro Gear and Transmission. The kit is built around the soft parts of a brake relay valve that wear first: seals, diaphragms, gaskets and springs. A relay valve passes the brake signal on to the brake chambers, so when it starts to stick or its seals wear, the truck can show slower brake response or uneven braking between axles. Servicing means taking the valve apart, cleaning it, and replacing the worn seals, springs or diaphragms before it goes back on the truck. Call us to confirm proper fit for your application.A factory handling fee of $20.00 per unit is added at checkout.FeaturesMaintenance kit for the R-12DCSeals, diaphragms, gaskets and springsCovers the relay valve parts that wear firstWorn relay valve seals can show up as slower brake responseGenuine Bendix part