Male threads to the airline. You can tell as the water drain is on that end. (tire valve) The must of screwed up the lable.
Put that thing on the end of you air hose, it is next to useless as a "full compressor" drain and only so so at water removal. There was a post a little while about this. There are 2 types that work well. The round paper filter ones and the descicant style. The deesign you have there is a small scale of one that is designed to be used after a long line of metal piping that is set up to cool the air, drop the water in the pipe and let it run to the drain seperate from the air. This would just help out at the end.