-Made from 7075 5/16" thick aluminum, each spoke is tapered and i-beam shaped for a tremendous strength to weight ratio. Industrial machine type tooth design for a smooth running drive train. The splined 19mm hardened steel center insert allows this sprocket to be used on 48 spline 19mm Profile type spindle only and eliminates the need to use the commonly used drive bolt. Weight: 2.6ozs. @ 25t.