As long as you have a hydotube already this replaces:
Bottomless banger for v4, m22, TRVP, and Sai.
14mm and 18mm glass adapters for v4.
All AVS airflow and mouthpiece upgrades.
Crossing 510 tether, and all carb caps.
And probably a lot more besides. Doesn't effect taste. Unbreakable. It's not even that bad as a mouthpiece, I just wish it felt a bit more teflon-like. Well worth the money and a lot more useful than the price would suggest.