Just when we thought we were done making bottom bracket sockets we get enough requests to add a fitment for Shimano STEPS drive units. This tool is used to remove the chainring spider from the drive unit. It's low profile clears chainring mount and it's relived internally to make room for the bottom bracket axle and the integrated washer that is found on some spindles. Other than that, it's a really nice 3/8" square drive socket just like the rest of our socket range.