This listing is for one Agilent G1958B Jet Stream ESI Source. The Agilent Technologies G1958-65538 (G1958B) Jet Stream Electorspray Ionization Source is compatible with the 6100 Series Single Quad LC/MS (6110/6120/6130/6140/6150). Electrospray ionization (ESI) is a mainstay of LC/MS that can be used to analyze large and small analytes. Electrospray Ionization (ESI) Source generates ions in a spray chamber then the system it is attached to then transports and focuses the ions into the ion trap mass analyzer. List price is about $35k! Set comes as pictured. This was an Agilent demo unit that saw very little use. Guaranteed functional once installed on a compatible spectrometer.