Brake master cylinders must be leakproof –, and stay that way. The outstanding features of Bosch brake master cylinders are their top quality and long service life. They are made of cast iron or aluminum. The high quality standard is guaranteed by sophisticated production methods and stringent checks, with tight tolerance specifications to ensure ideal functioning and freedom from leaks. Optimized cylinder surfaces minimize collar abrasion and help to maintain the long-term reliability of Bosch brake master cylinders.