Thexton Manufacturing's Master Cylinder Bleeder Upgrade Kit, No. 803UD, is for older Master Cylinder Bleeder Kits. The upgrade kit has the additional machined aluminum SAE and Metric adapters to bring original 803 kits up to 803X specifications. Included in the 803UD kit is a re-designed foam interior and a new plastic case. Used with the new U.S. and Metric Master Cylinder Plug Kit, Part No. 803P, the 803X kit allows the technician to bleed brake cylinders on or off the vehicle and to determine if internal seals are leaking.