Instead, it has a hardened CrMo steel insert in that matches up to the 48 splines on the crank axle for pure, direct power transfer. -Available for 19mm splined axles only. -1/8″ tooth width for use with most freestyle/street & single speed chains. -Supplied with 19mm splined steel insert. Sizes: 23t, 25t, 28t, 30t, 33t, 36t, 39t & 42t with 1