SF (Single Flange). Ready to run chrome plated wheel that is built with 48 chrome plated 8mm diameter steel spokes & nipples, a steel rim and an aluminum hub. Wheel is pre-sealed and suitable for tubeless tires. 1″ ID roller bearings are pre-installed and the brake rotor/pulley flanges come in H-D style mount pattern with56mm center. Front wheel for single disc is 5/16-18 UNC threaded. Total hub width 16cm.