Operable Windows Let fresh air into the building through a vent window that can be easily incorporated with Tubelite’s other framing systems. Special glazing pocket adapters make installation a breeze. These Curtainwall rated windows have a frame depth of 2″ with a maximum size of 3′0″ x 5′0″ and mitred corners epoxied and crimped on an “L” shaped clip. Standard and concealed project-out vent design, and casement options are available. The concealed vent design is virtually invisible from the outside of the building, with no visible frame. Screens are also available with frames finished to match the window.