The FR-3 is designed to fit the four-notch tool fittings found on SunTourA(R) freewheels made since 1986. Constructed from heat-treated alloy tool steel, the FR-3 features a 1" tool fitting for use with an adjustable wrench, socket, or bench vise. Fits 4-notch tool fittings with an approximate outer diameter of 24 mm Fits all SuntourA(R) four-notch freewheels since 1986 Center bore for axle clearance is 10 mm 1" hexagonal base can be used with 1" socket or wrench NOTE: The SuntourA(R) two notch freewheels do not accept the FR-3 remover. Use the FR-2 for the SuntourA(R) freewheels with two notches