If you're only rocking one gear sometimes you gotta do some cog swapping to ensure you have a tall or low enough gear for the ride. With Park Tool's Chain Whip/Sprocket Remover for 1/8in Cogs - SR-18. 2 you no longer have to settle for using a slipping 3/32in chainwhip while installing or removing 1/8in cogs often leading to bloody knuckles. The opposite side features a 1in box end wrench if your one-speed bike happens to have a freehub and the wrench is heat treated for strength while the molded handle provides comfort. Hardened pins keep the chains connected to the tool even if you're wrenching off a stubborn cog.