Product Details: Prepare your semi truck to be Ready for the Road Ahead™, with the Air Source 12V Relay Kit that provides enhanced control of a vehicle's electrical system. To help activate electrical mechanisms or control options, this replacement device sends a signal that can be used to distribute electricity or power components such as lights, motors, fans, and more. Fashioned with a weatherproof seal to endure poor weather conditions. FleetPride is your First Click in Heavy Duty®.