It only goes in one way.. and if you try to take it out now.. good luck.. they swell up quite a bit.. you may not be able to get it out. I am trying to remember what mine looked like, I believe there was a side with a protuberance (ohh big word for the day) it should have two "O" rings on it I believe.. that end goes in first.. flat end at the end of the tube.

Chad