It's the Rabbit Wine Aerator ... have you heard of this?
There's this one that actually slides into the bottle neck ...
And there's this one which works well for box wine. We do a lot of box wine drinking at our house so we had to get both.
The wine aerator works like a decanter and allows the wine to breathe. It makes such a difference! This handy device turns a $7 bottle of wine (our usual) into a $25 bottle of wine. The difference is truly amazing and totally worth the investment if you're a wine drinker. In my most sophisticated wine tasting voice, I tell you it takes the bite out of your drink creating a smoother body. My only complaint is that it's a little awkward to push the box wine spout while holding the aerator and your wine glass all at the same time. You definitely need a buddy ... or a third arm!