This mounting bracket is designed to attach to the backing plate, and hold the caliper in place over the edge of the brake rotor. The caliper contains the pistons and the brake pads that squeeze the rotor from both sides, and slow the turning of the rotor and thus the wheel via friction. As you can imagine, the caliper and the mounting bracket must both withstand a high amount of force every time the brakes are applied. This mounting bracket is made from a high quality material, so you can be confident every time you step on the brake pedal. This model will fit backing plates that are made by Tie Down, as well as any other backing plates that are compatible with Tie Down. They're also made only for use with disk brake rotors that are 12 inches in diameter. By purchasing your marine trailer parts from SkipperMate Marine, you can be sure you're getting great parts at great prices.