Caryaire Louver Model IL350 is Extruded Aluminium Drainable louver designed to have superior resistance to water penetration. Drainable louvers are characterized by gutters at the front edge of the blade to prevent droplets of rainwater from cascading from blade to blade and becoming entrained in intake Air flow. Vertical gutters in the Jamb frame carry the water to the Sil frame where it exits the louver assembly. Drainable Intake/Exhaust Louvers generally have an enhanced resistance to water penetration than conventional louvers.