Weight Saver & Waterproofing in One

I had the idea of putting my down sleeping bag in a waterproof stuff sack to make sure it stays dry. Obviously, this idea would extend to my wife as well. This solves both problems in one, as this sack is easily big enough to hold BOTH our 30 degree bags together, thus eliminating one stuff sack and two potential moisture issues. Seems like great construction for the very low weight.