Tri-Clamp Sight Glass - LongTri Clamp Sight Glass Long These tall sight glasses are a great additions closed loop extraction system to view the liquefied solvent flowing through your system and see the color before the purging process is completed. The short sight glass also allows the user to add a viewing port to their system without adding a lot of additional height compared to a normal Tri Clamp sight glass. Unlike many competitors, this sight glass is also nitrogen tested