Ultra-Prop Black Hubs are molded high-strength glass-reinforced composite with integral steel reinforcing plate. 6-1/2" OD. Fits 1" diameter prop shaft. Accommodating most mounting plate bolt hole patterns from 2-1/4" to 3-1/4" diameter and 1/4", 5/16" or 8mm prop mounting bolts. Assembled hub is 2-1/4" thick
