Disc Brake Caliper and Rotor
The caliper on a disc brake system is like a large hand holding a brake pad on the thumb and a brake pad on the fingers. The caliper lightly grips the rotor on each side. When brakes are applied, the caliper squeezes the brake pads evenly against both sides of the rotor to stop rotation of the wheel. This vehicle has recently been on the road as you can see the rotor is clean and shiny. You can also see that the rotor is in good shape, evenly worn, without gouging of any sort.