Arlington Industries F8091VC-1  Vertical Electrical Outlet Box for Siding with Clear Cover, White, 1-Pack Used for the fast and easy way to install fans or other fixtures, for 1/2-inch or 5/8-inch drywall L-shaped mounting box for fans or fixtures mounts securely to single or double joists with shipped in-place center screw Locator posts assure proper positioning of fan or fixture bracket Includes in-place center screw, installed NM cable connector, mud cover, two knockout holes and two-screws for installation UL rated at 70-pound fan, 200-pound fixture, CSA rated at 50-pound fan/fixture