- Insert the Flexible whistle alert into any spark plug hole and bump the engine until you hear the whistle blow. You are now on the Compression Stroke!
- Easily finds top dead center on compression stroke - quick and easy to use
- Rubber nipple adapts to any spark plug thread size
- Flexible hose allows for reach in tight spaces.
- Made and assembled in U.S.A.
No more burning fingers and hands. Just listen for the whistle to find the TDC Compression Stroke.