The Seasons Through the Wall Air Conditioner Sleeve is used when installing TTW (Through The Wall) model air conditioners. This is a universal design that should work with most 24 in. TTW models on the market. Wall Sleeves are recommended to be installed by a professional and designed to hold TTW air conditioners that have a rear venting system. For proper water drainage, make sure the air conditioner is slightly tilted downward from the front of the unit to the rear.