This is a pack of ten 5x13x4mm rubber sealed "Speed" 1/8 clutch bearings. ProTek R/C "Speed" bearings are high quality steel/chrome bearings designed for the R/C racing enthusiast. 

These 5x13x4mm rubber sealed bearings are the standard bearing for the Team Losi 8ight inside clutch bearing. Please check the manual that came with your vehicle for the correct size if you are not certain.