Power Probe's Key Assist puts a single technician in complete control of the vehicle’s ignition key to remotely start and stop a vehicle's engine. Great for use with repairs on the engine, drivetrain, electrical system or exhaust system. The Key Assist allows users to crank the engine from under the car, the hood or from either side of the vehicle. Ideal for compression testing or bumping the engine to TDC (top dead center) timing marks for valve, distributor, camshaft adjustments. Also an excellent aid in performing voltage drop tests.