Bulkhead tank fittings are usually installed near the bottom of a container. There is a sealing washer included to keep the tank fitting sealed against the container wall. The inside threads are 3/4\” NPT to allow many different types of fittings or valves or cam lock couplers to thread into the center of the tank fitting. External thread and nut are left hand threads Internal thread is female pipe tapered thread For use with tanks having a wall thickness of 1/16\” to 1/2\” Body and nut are nylon Friction washer in polyethylene Sealing washer is buna FDA approved