Top Shelf TSB-2438 Air Conditioner Bracket, White Installs from the inside in just minutes No drilling, tools, hardware or fasteners required Adjustable for single or double hung window from 24" to 38" wide Note, if your window is flush to the exterior (no exterior sill or ledge), the typical wall thickness is about 4". The TOP SHELF A/C Bracket will not work with a flush mounted window as it requires a minimum wall thickness of 6". Mounting Capacity: 6-12 wall construction