Get your semi truck Ready for the Road Ahead with enhanced trailer brake control, with the Bendix 1.61" MV-3 Trailer Air Valve Knob. To facilitate the quick evacuation / supply of the air brakes, this replacement knob can be mounted on the interior dash of a vehicle. Built with an ergonomic and streamlined design for regular use in daily operations. FleetPride is your First Click in Heavy Duty .