●Material: these bearings are made of bearing steel for low noise, and have good anti-rust performance as well as long service life. ●Rubber side seals: they are lined with rubber to prevent contamination from entering and save lubricant. ●Application: suitable for all types of hybrid/comfort bicycles, road bikes, industrial equipment, micro motors, small rotating motors, office equipment, etc. ●Rolling element: can maintain the distance between moving parts to reduce rotation friction and carry radial and axial loads. ●Note: please refer to the picture and select the correct bearing type before placing your order