Holds it in!
I have one of these liners, but I don't use it in a pail. It keeps smells in REALLY well. So well that I nearly fall over from the smell when I put everything in the laundry since I'm not expecting it! The one downside is that if you have LOTS of wet/soiled diapers in it, it will eventually begin to wick through. Not enough to make everything outside the bag wet, but just enough to make it damp to the touch. Though I do mean LOTS (about 3+ days worth of diapers), this thing can hold a TON.
Reviewed by: Misty Henry from Evansville, IN.