Material : 7050 alloy, T6 heat treated. Shadow pedal boss system. 4130 heat treated chromoly 22mm 16 spline and internally butted Spindle. Hollow heat treated pinch bolts. Hollow 7075 alloy crank bolts. Hollow heat treated pinch bolts. Crank arms are drilled to accept micro gearing. Includes 22mm sprocket spacer. Weight : 32oz.