Housing cast of heavy-duty 85-5-5-5 naval bronze; machined with tapered pipe threads (NPT) Chromed bronze ball for maximum saltwater corrosion resistance; SS ball stem Grounding screw for connection to the boat's bonding system, (sizes 1/2" to 4") Drain plug for easy winterizing (sizes 3/4" to 4") Handles are coated with a thick, non-slip plastic for a sure grip Bronze body/SS hardware - cathodic protection is required; includes grounding screw for connection to the boat's bonding system