Used on Dico Titan model 6, 10, 20 and 60 surge brake actuators. Can also be used on some Atwood models. When energized, lock-out valve prevents the flow of brake fluid to the trailers hydraulic brakes when backing up. Threads into rear of actuator master cylinder with 18 treads. Eliminates the need to manually activate the brake lock-out when backing up. Must be wired to tow vehicles backup light circuit. California Residents WARNING Cancer and Reproductive Harm - P65Warnings.ca.gov Other Deta