In order to have a better anti-rust effect, we use stainless steel AISI440C/AISI304/AISI316 and but some high-class fields customers like to use full Ceramic Like Zirconia Ceramic, and Silicon Nitride ceramic. The medical industry has a higher accuracy requirement on bearings, so we provide ABEC-5 Level bearing, sometimes we even can achieve a higher level of ABEC-7.