The BSD Back Street Pro cassette hub features a 6061-T6 aluminum hub shell.It includes two precision sealed bearings, a 17mm hollow heat-treated chromoly axle w/ (14 x 1 mm) heat-treated axle bolts, a 1pc chromoly driver w/ skip free mechanism for reliability, a 3-pawl engagement system, and a polymer driver bushing for smooth, lasting operation. It features a machined BSD logo.

Center Axle:17mm Hollow Chromoly
Axle Bolts:14 x 1mm Hollow Chromoly
Driver:1-pc Chromoly
Driver Pawls:3 Pawl
Driver Spring:3 Individual
Weight:17.2 oz