A hydraulic braking system effectively has two lines that carry the brake fluid from the master cylinder to the calipers. The rubber brake hoses are flexible and carry the fluid right to the calipers to induce the friction required to stop the wheels moving. These hoses are connected to the steel brake pipes that are permanent, immovable and usually located in the wheel arches. Metal brake pipe unions are used to connect the pipes and hoses in the braking system. This ultimately ensures that the fluid can be delivered to the calipers when the brake pedal is pressed, so the driver and passengers can stay safe on the road.