With no moving parts to wear out, your AFO will stand the test of time. It is the only air brake system that energizes the towed vehicle's power brakes through a patented process that doesn't require an electronic vacuum pump. It uses a pilot signal from the coach's air brake system to deliver 100% direct proportional braking. And in the event of a separation of the coach and towed vehicle, AFO is the first and only supplemental brake system that seals the coach's air supply.