smaller than my boot!
A shelter that can comfortably sleep three big guys and a week's worth of backpacking gear, yet squishes down to about the size of a water bottle is hard to beat for going lightweight.
It is not without its drawbacks, however. As some reviewers noted it can get a little clammy inside; also, the lack of floor could become problematic during heavy rains but a cheap ground tarp and a thick sleeping pad are enough piece of mind for me.
It's a little pricey for a glorified tarp (especially if you were to buy the floor or bug net) but if you're concerned about saving room in your pack for important things like snacks and you've got a backpacking buddy to split the cost, it's way worth it.