Park Tool's patented GearClean Brush has a unique design. A large comfortable handle with a curved, toothed-end reaches dirt deep between the gears, and tough nylon bristles clean the derailleur and chain. Saves wear and tear on your chain and freewheel. Works great on brakes or other places where dirt collects. Handy size to take along for quick cleaning anywhere. Fit narrow spaced 9 and 10 speed cassettes. Made of sturdy nylon.