The TRW Master brake cylinder (PMF138) is a professional-grade replacement component engineered for long service life and reliable operation across all conditions your vehicle encounters. The part is built to the following specification: Manufacturer Restriction: ATE, Diameter 1 [mm]: 20, Plastic mm, Number of connectors: Copper, Thread Size 1: M10x1. Each dimension is checked against the OEM reference to ensure the component seats and functions correctly first time. Verified to fit BMW models. All compatibility data is cross-checked against the TecDoc database — select your vehicle to confirm the part matches your specific engine and year. This part supersedes original equipment references: 03.2120-0242.3, 03.2120-0622.3, 0 986 480 100, 1 117 208 and 32 more. Matching these numbers confirms a like-for-like replacement with no loss of function. TRW is a recognised supplier of automotive braking components to independent workshops and dealer networks across Europe. All parts are sourced from authorised distribution channels and carry full manufacturer traceability — you receive exactly the same component supplied to professional garages and dealer workshops. If fitment or specifications do not match your vehicle, our technical team can help identify the correct alternative — use the vehicle selector or contact us with your VIN for a guaranteed-fit recommendation. Replacing worn components on schedule preserves your vehicle's safety, reliability, and resale value — and aftermarket parts from established brands deliver OEM-equivalent performance at a fraction of the dealer price. Every part is dispatched from our UK warehouse with a 30-day money-back guarantee and free hassle-free returns.

TRW Automotive, with roots dating back to 1901 in Cleveland, USA, is a global leader in safety-critical automotive components, now part of ZF Friedrichshafen. TRW specialises in brake pads, brake discs, steering components, suspension parts, and engine valves. As an OE supplier to virtually all major global car manufacturers, TRW products meet the highest safety and performance standards. Trusted by vehicle makers for over a century, TRW delivers braking and steering components that prioritise safety without compromise.