These Agilent Varian HS-20 diffusion pump jet assembly are OEM Agilent Varian replacement parts for the HS-20 diffusion vacuum pumps. This kit includes the complete jet assembly components, see the jet assembly referenced on page 40 in instruction manual PDF below. These are original OEM Agilent Varian replacement parts for the HS-20 diffusion pump having part number PN 84350301, see item #3 in the diagram exploded view & parts illustration below.