The Revo 2.5r and Savage both use a 6x10x12 one-way bearing. The Savage has a hex shaped adapter over the bearing that can be pressed off the bearing and pressed onto a new bearing. I buy the one-way bearings from avidrc.com to replace mine when they go bad, but I prefer the INA bearings from Germany. They're just a little harder to find and cost about twice the price.