These residual check valves help keep the brake system functioning properly, while also helping to retain a firm pedal. Maintaining pressure prevents fluid from returning to the master cylinder, when the master cylinder is positioned lower than or close to the same height as the calipers or wheel cylinders. Proper system pressure also keeps pistons and wheel cylinder seals expanded, creating a positive seal, and brake pads seated against the rotor.
3/8 UNF inverted flare adapters are required for these valves