1,Long working life 2,Anti-rust and waterproof 3,Low price and good quality 4,The materials are bearing steel ... 2) equipment, instrument, building machinery, rolling stock agricultural machinery and various specialized machineries. 2. About product: 1) Types: 6000 ... series,6800 series3) Material: Carbon steel,Stainless steel,Chrome Steel and Bearing steel4) Shield / Closure: Plain (Open), Z, ZZ, ...