The Keystone 26-inch wall sleeve for through-the-wall air conditioners should be securely fastened within a wall opening before installing the air conditioner. The sleeve helps bear the weight of the air conditioner while keeping it insulated and safe from dust, bugs and other debris that could get sucked into it. Inclement weather, corrosion and other elements cannot match the protective power of this metal sleeve. Use in finished walls up to 17.75 inches thick. Gender: unisex.