Motion Pro is dedicated to producing the most versatile, unique and durable products for professional and home use. Motion Pro tools are designed to be simple to use, yet durable enough to withstand the harshest conditions. One of their goals is to offer tools of convenience. Do it right the first time with Motion Pro Tools. Kit includes an extended thread adapter and dial indicator extension. Allows the Motion Pro Water-Cooled 2-Stroke Timing Kit (P/N 08-0250) to be used on air-cooled engines with 14 mm spark plugs. Adapter length installed is 55 mm. Outside diameter is 19 mm. Note: Adapter kit does NOT allow the two-stroke timing kit to be installed on Yamaha RD two-stroke twins with the engine installed in the frame. The kit does work on Yamaha RD two-stroke twins with engine OUT of frame.