Master Cylinder Repair & Rebuild Kit - .625" 15.88mm 5/8 OBPRP625 Part Number: OBPRP625 As master cylinders get older they can lose performance from fluid leaking past the piston seals. These obp Motorsport rebuild kits offer a cost effective alternative to replacing the whole cylinder. This repair kit supplies all the components required to make your master cylinder perform like new. The kit contains: • All seals • Piston • Spring • Operating Rod