Bearing type: 6701ZZ / 6701- (different manufacturers, the bearing model (code) will be expressed differently. Such as 608Z = 608ZZ = 608-2Z = R2280ZZ = MR608Z = RV822, etc., All models in the title are the same bearing, please order according to the bearing size.) Bearing size: inner diameter * outer diameter * width = 12 * 18 * 4 (mm) Abec1 The dimensional accuracy is less than + 0.05mm and the speed is less than 500 / min, which is suitable for low speed and low requirement environment. Such as: low-speed transmission equipment, casters, children's cars, toy cars, etc. ABEC3 The dimensional accuracy is less than + 0.01 mm, the handle is smooth, the rotation speed is less than 6000 / min, the noise is low and the service life is long. It is suitable for motors, model cars, automobiles, power tools, pneumatic tools, telecommunications equipment, fitness equipment, sports equipment, etc. ABEC5 The dimensional accuracy is less than + 0.005 mm, the handle is smooth, the speed is greater