Suitable for all popular non-adjustable GM type combination valves. Used to lock the low pressure exhaust valve, allowing the braking system on PV2/PV4 to exhaust quickly and easily. Made from high-quality, durable materials. Specially designed for CPP proportional valve to prevent the combined valve from tripping. Tool is designed to lock the low pressure shut valve to allow fast and easy brake system bleeding. Brake Proportioning Valve Bleeder Tool is new and specially designed for CPP proportional valve, preventing combination valve from tripping. Compatible with DISC/DISC and DISC/DRUM PV2 and PV4. Suitable for AC 172-1353 and 172-1371. Color: Blue. Material: Metal. Package includes: 1 x Brake Proportioning Valve Bleeder Tool. Eliminates the need to constantly remove the low pressure switch or center the low pressure valve during the brake bleeding process.