Set of 2 6301ZZ double shielded scooter wheel bearings Also commonly referred to as 6301Z series 30 Day Warranty Description Set of 2 6301ZZ double shielded scooter wheel bearings. Also commonly referred to as 6301Z series. Shielded (ZZ or Z suffix) scooter bearings of this size are commonly used in wheels, transmissions, gearboxes, and various other GY6/QMB139 engine components. These single-row, deep groove ball bearings are designated as medium-weight and feature a 12 mm diameter bore hole. Be sure to check your existing bearings for the series number, which is often etched onto the outside wall of the bearing. Specifications Diameter (Outer): 37 mm Diameter (Inner): 12 mm Width: 12 mm