The Ratchet Hub Guard uses 2014-T6 Aluminum to keep the strength high, weight low and price affordable. The guard replaces the steel collar on the Ratchet Hub, for a perfect fit and no spreading your frame's dropouts to get it to fit. Steel insert inside the aluminum keep the fit perfect no matter the abuse. Best used with one of the 5 ribs in the backside of the hub down, centered with your grinding area.