Purist bottles are the best, hard stop, but this WaterGate cap makes me want to scream. The one positive of the cap is that it does not leak, even in the open position. But the negatives, my goodness. You have to squeeze the bottle so hard to get water to come through that if you're tired in any way you might not be able to activate it. And when the seal finally does open, you're going to shoot water into your mouth and down your throat at a rate that could choke you if you're not ready for it. AND the valve doesn't bring air back inside in the reverse direction so now your bottle is permanently squished until you can get on a flat and unscrew it enough to let air back in. This thing is terrible. I have other caps that work just fine so no losses here, but man, don't buy this cap — buy a Purist with a standard cap.