New Danby Air Conditioner

@RayjoeJim, those clips are little pieces of plastic that rotate clockwise when you turn/tighten the screw. These "ears" which rotate trap the receptacle box in place with your plywood bulkhead/wall (or sheetrock in a house.) You can probably find replacement boxes at any HomeDepot/Lowes/bigbox store with the name of something like "cut in box", typically the plastic is a bright blue color.