Before the introduction of the euro, francs were also used in France, Belgium and Luxembourg, while Andorra and Monaco accepted the French franc as legal tender (Monegasque franc).
Inside the caliper is a brake pad, a small block of friction material backed with a metal plate. When you step on your brake pedal, pistons inside the caliper cause it to apply pressure to the brake pad which squeezes the rotor, causing the car to slow or stop.
Most vehicles have what is known as sliding brake calipers. A piston (or pistons) inside each caliper presses against the inner brake pad, pushing it against the brake disc. The outer pad is pulled against the brake disc as the U-shaped caliper body slides in response to piston movement (see illustration).