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.
A car can have either 2 or 4 calipers. If the car has rotors on all four tires, then it will have four calipers. If the car has two rotors and two drums, then it will come with two calipers in front. The calipers can become contaminated, rusty, and start to leak brake fluid.