For use on 1-3/4″ x 1-1/4″ tapered spindles. 6 stud with 6 on 5.5 bolt pattern. 12″ Rotor With Model 800 Disc Brake Actuator. Kit comes with everything needed to replace or upgrade the hydraulic brake system on your trailer from drum brakes to vent rotor disc brakes. Includes disc brake actuator, brake lines for a single axle trailer and two vented rotor disc brake assemblies with integrated hubs. Integrated hub and rotor feature GalvX finish for added corrosion protection. Vented Rotor, Aluminum Caliper and 2 piece piston dissipate heat faster. Actuator feature Drop N Go Auto Latch Coupler.