This is a pack of ten 10x15x4mm metal shielded "Speed" ball bearings. ProTek R/C "Speed" bearings are high quality steel/chrome bearings designed for the R/C racing enthusiast.
These 10x15x4 metal shielded bearings are the standard bearing for Xray hubs and 1/8th scale on-road hubs. Please check the manual that came with your vehicle for the correct size if you are not certain.
Note: This list may not be 100% accurate or up to date, and is meant to be used as a guideline for compatibility.