This is a pack of ten 5x11x4mm metal shielded ""speed"" clutch bearings. Protek r/c ""speed"" bearings are high quality steel/chrome bearings designed for the r/c racing enthusiast. These 5x11x4mm metal shielded bearings are the standard bearing for many monster truck clutches, such as the traxxas t-maxx and traxxas revo. Please check the manual that came with your vehicle for the correct size if you are not certain. (ptk-10037)