The deep groove ball structure is also divided into two types: sealed and open. The open type means that the bearing does not have a sealed structure. The sealed deep groove ball is divided into dust-proof seal and oil-proof seal. The material of the dust-proof sealing cover is stamped steel plate, which only serves to prevent dust from entering the bearing raceway. The oil-proof type is a contact oil seal, which can effectively prevent the grease in the bearing from overflowing.

The iron cover seal bearing, or called Metal sealed bearing,  is divided into bearing steel sheet seal and stainless steel sheet seal. Bearing steel sheet seal easy to rust, stainless steel sheet seal it is not easy to rust, which can prolong the service life of the bearing. This type of bearing is suitable for places with high speed and high temperature.