This Agilent Varian HS-20/32, NHS-35 diffusion pump cold cap female coupling, is part of the cold cap assembly and is an OEM Agilent Varian replacement part for the HS-20/32 and NHS-35 diffusion vacuum pump. This is an original OEM Agilent Varian replacement part for the HS-20/32 and NHS-35 diffusion pump having part number 622445026, see item #18 in the diagram exploded view & parts illustration below.