These Agilent Varian VHS-400 diffusion pump jet assemblies are OEM Agilent Varian replacement parts for the VHS-400 diffusion vacuum pumps. This kit includes the complete jet assembly components, see the jet assembly referenced in Page 42 in instruction manual PDF below. These are original OEM Agilent Varian replacement parts for the VHS-400 diffusion pump having part number F0428401, see item #2 in the diagram exploded view & parts illustration below.