By Emily Stifler Explorebigsky.com Managing Editor

This might very well be the smallest backpack ever.

I regularly use it grocery shopping—stuffed into its tiny built-in stuff sack, it takes up the same amount of room in my purse as my wallet. When expanded, it holds 5.28 gallons (20 liters).

I tried to give this bag to one of my rafting co-workers, but she turned her nose up at it—classic boater, thinks she can take the kitchen sink everywhere she goes! But I’m a climber, and a well-made summit pack that weighs only 2.4 ounces appeals to my alpine sensibilities, even if I’m only going for groceries.

And of course, there are outdoor applications, too: Last week I went up to do some work on a rock climb one evening in Gallatin Canyon. Hanging on a rope, scrubbing holds and checking things out, I wanted to bring along sunglasses, a long sleeve shirt and my climbing shoes. But packing up at the car, I instantly rejected my regular bullet pack, not wanting to carry the extra weight. Bingo: the ULTRA Sil.

I haven’t really done enough all-out grocery shops or summit pushes with this pack know how durable it is, but it’s made from “siliconized” CORDURA, which sounds wicked tough, plus the stress points are all reinforced with bar tacks. Still, it’s so lightweight I’d say it’s definitely not made for hauling or chimneying on rock climbs, or dragging behind your car.

Basically, this is a very cool niche item. Without any pads in the shoulder straps, it’s definitely not made for carrying heavy weight. But for shopping, a summit push or just to have an extra tote while traveling, it’s just right.

seatosummit.com