Features: Tool whistles as the piston approaches Top Dead Center (TDC) on the compression stroke and stops whistling when the piston reaches TDC. Helps to eliminate the guesswork involved when diagnosing jumped timing belts and timing chains. Aids in valve adjustments and installation of distributors, timing belts and timing chains. 2-in-1 fitting threads into all 14mm and 18mm spark plug ports. Overall length of 27″. Not for use on diesel engines. Instructions included.