100 percent solid-state electronic, designed for use with 2 to 8-brake systems. Overload and digital output indicator. Thumb wheel adjustment, control rate from soft to aggressive. No moving parts or pendulums; no leveling required. Compatible with anti-lock braking systems. Covered by additional circuit protection, will not be damaged if black and white wires are reversed, or if there is a poor or no ground and a short occurs. Slim, contoured for more under-dash clearance. Mount in any position, mountingbracket and hardware included. Meets all national highway traffic safety administration regulations regarding tow vehicle/trailer stoplight activation. Not recommended for use with BMW X5 SUVs.