DESCRIPTION 2 LB Residual Check Valve --Brand new 2-pound residual pressure valve in blue. --This valve can be used with any disc brake application as long as the master cylinder is located under the floor. --Input Threads: 3/8"-24 --Output Threads: 3/16" Compression fitting --When the master cylinder is under the floor, it is usually lower than the calipers. --Gravity and vibration can cause brake fluid to leak back to the master cylinder away from the calipers, causing a loss of brake pressure. --This valve acts as a one-way check that prevents this type of bleeding. --Without it, your brakes could drag or give out completely. 10 LB Residual Check Valve --Brand new 10-pound residual pressure valve in red. --The valve is used with any drum brake application where the master cylinder.