The RAVWPT15 features a telescopic design and can accommodate a range of different wall thicknesses from 8" up to 15". It features GE's QuickInstall 2-piece design which allows for plenum assembly before installing in the wall. This design also allows for interior installation with no need to access the exterior of the building. Also included for installation is a 1.25" thick gasket that assures a complete seal between the plenum and unit eliminating outdoor air or moisture from entering the space. For easier installation, Grille Kit (RAVAL3) should be installed at time of Wall Plenum Installation.