The stainless steel shaft coupling is made of 304 stainless steel. It is also can made of 316 stainless steel if you use it on marine. It is a new type stainless steel coupling. It doesn’t have thread holes. The stainless steel quick coupler will be cut, and CNC machined from a round bar. After CNC machined service, the surface roughness is Ra 3.2. It also can reaches Ra 1.6 or Ra 0.8, it is on demand.