... ) 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, ... RS, 2RS, 2ZR, 2Z. 5) Vibration and Noisy level: Z1, 6) Precision level: ABEC-17) Brand: ALZ ...