A Brake Caliper is the hydraulic housing that straddles the brake disc and presses friction pads against both of its faces to generate braking torque. A floating caliper has pistons on one side only and slides on pins so the reaction clamps the opposite pad, while a fixed caliper is rigidly mounted with opposed pistons on both sides, which gives more even pad loading and a firmer pedal because there is less to deflect. Total piston area, along with master cylinder size and disc diameter, determines the clamping force and therefore the front-to-rear brake bias, so caliper changes at one axle alter braking balance and can require proportioning correction. Caliper stiffness matters as much as its piston area, since any deflection under pressure is pedal travel that does no braking work, and caliper mass is unsprung weight.