... to make sure bigger air capacity,higher efficiency,longer lifespan.Bearing (Sweden SKF)Perfect stability,adapting to changeable load ... speed,decreasing abrasion of bearing;Lower running temperature,decreasing load of bearing;Higher accuracy of bearing,longer lifespan.Electricity Board (Siemens ... ,protection class IP54,F class insulation,SKF load bearing,higher efficiency than similar products by 3%-5%. ...