A scooter brake is what you assume, it helps slow you down! But you should only use the brake within reason and softly !! The brake should be treated more as a back wheel guard to protect your foot from hitting the wheel which is dangerous and can end badly! A major problem is when riders (more commonly younger and less experienced ones) use the scooter brake too hard and skid the wheel, this creates a flat spot on their back wheel, which results in needing a new wheel. Brakes are often unique to the scooter deck so changing them requires getting the correct brake that matches that scooter deck. Scooter brakes can be replaced but the effort required to do the swap over depends on the condition of the deck. Sometime they can be very difficult to swap over.