Very useful tool, this locks the primary sprocket and clutch chainwheel. You can then undo engine sprocket nut and clutch with minimal effort.
This tool fits the 1H 2T 3T 4T motors. Please note on some 3Ts and some electric start 4Ts a 25 tooth primary sprocket is used instead of the standard 20 tooth sprocket. If this is the case, you need part No. ST1380.