The Attwood trailer brake system adds safety and convenience to trailer towing with benefits such as no "in car" hook-up, no hand controls, and no special car-to-trailer wiring. Designed to provide reliable and efficient automatic braking for towed equipment applications. This system offers the benefits of superior braking performance while being compact and lightweight. A manually operated brake lockout lever prevents the trailer's brakes from applying while backing up over soft ground or uphill. SAE Class 4 for bolt-on 3" channel or weld-between applications up to 6,000 lbs. G.V.W. 3" tongue width. 2" ball.