Some bivy sacks are heavier than solo tents; others don't offer enough protection. This one hits the sweet spot, thanks to a durable, polyurethane-coated nylon ground layer and an ultralight silnylon top.
A half-length zipper provides venting and easy exits. I used it as a ground cloth while sleeping under the stars in Colorado National Monument; when a shower passed around 3 a.m., I just slid inside and stayed dry.
Pros: Compact as many emergency blankets, but way more durable and weatherproof.
Cons: It comes packed as small as a Coke can, but you'll never compress it that tiny again (use the 9-by-4-inch stuffsack). msrgear.com