1-1/2 inch carbon steel main ball rotating on carbon steel 3/16 inch support balls in a precision formed carbon steel housing. Hudson bearings is an innovative domestic manufacturer of ball transfers. flange-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. flange mounted transfers can be used in either ball up or down position.