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.
Know your calipers: The majority of cars have a sliding caliper brake assembly. That's what's shown in the photo above. Compare this brake assembly to the one in your car. Other cars have fixed caliper assemblies.