The company uses high quality steel GCr15 as material，mass produces zhe low noise bearings as follows， Model:1601,1602,1603,1604,1605,1606,1607,1614,1615,1616,1620,1621,1622,1623，1628,1630,1633,1635，16001,16002,16003,16004,16005 Spsc;ZZ Z 2RS RS OPEN NR 2RSL
