Brake Pressure Gauges make diagnosing your brake issues simple. By checking your brake pressure at the caliper or wheel cylinder you can determine for: Proper Master Cylinder bore size Master Cylinder & Power Booster function Mechanical vs Hydraulic issues Faulty Proportioning Valve Front to Rear Brake Bias & Much More Brake Pressure Test Kits include: Brake Pressure Gauge, 5/16-24 Adapter, 3/8-24 Adapter, M7x1.0 Adapter, M8x1.25 Adapter, M10x1.0 Adapter, M10x1.5 Adapter, Instructions & Solutions Guide.