HPAC test bottles, if you give Trevor a ring he can tell you prices etc, then you can just post the bottle to him and he will test it and post it back. would be better if you know somebody who plays at tournaments as they could give it to him at an event and pick it up for you at the next one to save postage. or you could come down yourself and see the tournament side of paintball as well as see lots of other kit and possibly pick up a few bargains 