Agilent Varian VHS-250 Air Cooled Diffusion Pump Replacement Standoff Ceramic Bushing Insulator, for Cold Cap.
Agilent Varian PN 699006025
Agilent Varian VHS-250 Air Cooled Diffusion Pump Replacement Standoff Ceramic Bushing Insulator, for Cold Cap.
For location see item #19 on illustration below.