We got these with my son, and he didn't take a bottle often, but when he did he never had a problem emptying it with these bottles.
I dont' know if the anti-gas factor of these bottles was ever necessary for my son, but I liked that we had it anyway! it can't hurt, right?
The only downside with these bottles is the extra peices to wash. (and we didn't have a dishwasher). But it was fine since he didnt' use them often. and if he did use them often and we had a dishwasher, it wouldn't have been a big deal.
4.78 overall from 23 reviews
from $4 at 2 merchants