Wanna run a single-speed or fixed-gear on your current bike but have vertical dropouts? This hub allows you to do that. Eccentric axle allows the hub to pivot to tension the chain. This unit is a 32 hole model, 135mm width to fit mountain bikes. Accepts a freewheel on one side, a 6-bolt rotor on the other. Inlcudes the White Industries eccentric disc brake caliper bracket.