The All-City Master Dropout is a sliding dropout system consisting of replaceable dropout plates and fixing hardware. Designed for use with 12mm thru-axles and flat-mount brakes, it is compatible only with select All-City models. - Allows riders to convert from a geared to single-speed setup or vice-versa - Compatible only with select All-City models - No additional chain tension adjustment required - Threaded cap / nut for axle installation - Cap nut and O-ring included - Use with drive-side plates