Through-the-wall air conditioners install into a cutout in an exterior wall. They cool a single room and install in a wall sleeve, which provides a permanent, stable platform for the unit. Units with a slide-out chassis allow easier access for service and repairs than fixed-chassis units. Through-the-wall air conditioners don't require connection to ducts. Units for cooling only are used for seasonal cooling or for supplementing central AC systems. Units with heat provide cooling and heating from a single unit for year-round use. All commercial grade and residential units have a leakage current detector interrupter (LCDI) that senses current leakage and interrupts a circuit to help prevent injuries and damage to equipment or surroundings. Some units have Seacoast corrosion protection, which is a coating on an air conditioner’s coils that withstands corrosive agents such as salt water sprays. Coated coils typically last longer than uncoated coils in coastal areas and other harsh environments.