This fixture is made of high quality composite plastics that do not corrode, peel or rust and stands up to the harsh salt environment of the oceans. It is intended for use outdoors/wet locations. It may be mounted on a 1/2" PVC pipe or a 3" PVC post. The "O" ring in the housing makes it water tight. All hardware will not rust as nylon or stainless screws are used. The actual fixture size is 6 1/4" wide by 10 3/4".