Park Tool SR-2.3 Sprocket Remover/Chain WhipThis shop quality chain whip gives you incredible leverage without worry of slippage, and the head is uniquely shaped to allow quick and accurate access to any cassette. Specifications Works on 7 speed to 12 speed mountain and road bike cassettes as well as single speed cassettes with a 3 32" cog Hardened bolts hold securely and make chain replacement easy Heavy duty, heat treated head Round vinyl coated handle The SR 2. 3 is approximately 15" long