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 performance calipers are made of lightweight aluminum, which runs much cooler than cast iron, prolonging brake fluid and brake component life. Aluminum is also much lighter than cast iron, which lowers unsprung weight, lessening the work that your suspension has to do and improving handling.