Hudson sbt-1ss-1/4-20 1 stainless steel ball 1/4 stud in stainless steel housing hudson bearings is an innovative domestic manufacturer of ball transfers. stud mounted units feature a hardened and zinc plated mounting cup and a foam seal. housing options include stainless steel with option for felt seal. main and support ball options include stainless, nylon, phenolic, and delrin. stud mounted transfers can be used in either ball up or down position.