Southwest Wheel Pro 3,500 lbs. Trailer Axle Electric Brake Kit 5-5.5" Bolt Circle. 10" Electric Trailer Brake Kit for utility trailers, travel trailers, horse trailer, motorcycle trailers, and more. Comes with Genuine Timken bearings & seals. Lug nuts, grease caps, cotter pins, spindle washers, spindle nuts, and brake mounting washers and nuts are included. A pair of 10" x 2 1/4" 5-5.5" bolt circle TruRyde hub and drums with parts (3 1/4" from center of one stud to the center of the next stud), and a pair of 10" x 2 1/4" TruRyde electric backing plates. This kit includes genuine timken bearings & seals. Timken parts are stamped made in the USA. TruRyde parts are manufactured to automotive standard in ISO/TS-16949 registered factory. All studs are 1/2"-20 with yellow finished zinc plating. Hubs are chemically cleaned and painted black in electrostatic booth. Backing plates are CSA compliant. SAE rated friction material. Magnets tested 100% for pull force and conductivity. Comes with Southwest Wheel bolt circle guide to insure you received the correct bolt circle.