Park Tool FR-4 Freewheel Remover Remove and install your freewheels with ease and efficiency using the Park Tool FR-4 Freewheel Remover. It's made from heat treated alloy steel and features a 1" base that fits a wrench or a bench vice for those hard to budge freewheels. The thin wall construction allows you to remove the freewheels without the need to remove cones and locknuts. Features Fits Atom(R), Regina(R), splined Zeus(R), and some Schwinn(R)-approved freewheels The FR-4 has 20 splines and is approximately 21. 6mm in diameter Always use a skewer or axle nut to hold remover firmly in place Related Articles: CASSETTE AND FREEWHEEL REMOVAL AND INSTALLATIONManufacturer's Part No: FR-4UPC: 763477003478 | Park Tool | Fr-4 Freewheel Remover For: Atom, Regina, Splined Zeus