10″ x 2-1/4″ Left Hand electric complete brake assembly. 3,500lb capacity per pair. Mounts with 4 bolts (included). Bolts are 2-7/8″ apart, center to center. The self-adjusting feature automatically adjusts the brakes after the initial installation. Uses 10″ Hub/Drums.nNuts-6-17 includednWashers-5-8 sold separatelynnThese components have passed the CSA Standard CAN3-D313-M85 For Trailer Running Gear, a stringent standard mandated by the Government to assure brake effectiveness and structural integrity of the components. ISO/TS 16949:2002.nn* Fits standard 3,500lb axle with a 4 bolt pattern on the mounting flange.n* Left Hand(driver's side)n* Self-adjustingn* Complete assembly ready to bolt on and wiren* For use with a 10″ inside diameter drumn* The shoes are 2 1/4″ widen* Mounting hardware includednnTo determine the size of the brake, you need 2 measurements. The first is the diameter of the brake(D). The second is the width of the shoe(W). It is good to take note of how many mounting bolts the brake has.