For use with our fresh water tanks equipped with 1-1/2" FPT fittings.  Just screw the 1-1/2" MPT end into the tank and attach a 1-1/4" clear vinyl hose or 1-3/8" green corrugated hose. A hose clamp finishes the job.  No thread tape is needed when screwing plastic fittings into polyethylene tanks.  Just go one turn past hand tight.