Let’s say you’re interested in ultra lightweight backpacking, but aren’t quite ready to sleep in a cocoon of a bivy shelter. Or let’s say you’re not an extremist, but want to allocate your pack pounds to other comforts besides your shelter. For the sake of argument, let’s also say you’re willing to budget big for this experience.

Enter the Sea to Summit Duo Specialist. This little wonder looks and feels like a tent–you can actually sit up in it, imagine!–but carries like a bivy. In fact, it’s lighter than most extreme lightweight tents out there, weighing in at only 22 ounces. Yes, really. And did I mention you can sit up in it?

Here’s the nitty gritty: The Duo weighs in at 846 grams (there’s also a Solo weighing 625 grams…more on that later), making it the lightest fully-enclosable shelter in its class. (Now I sound like a car commercial, but no matter.) The Specialist comes with a set of two poles and six pegs made out of 7075 alloy, but can also be erected with a pair of trekking poles and natural anchors if you want to achieve low-weight nirvana (633 grams for the Duo).

The shell is made of Pertex Endurance, which is basically an ultra lightweight waterproof breathable nylon fabric. It’s seam sealed throughout, which means it’s waterproof enough to act as its own rain fly. The mesh doors (there are two) offer much-needed ventilation (I’ve found moisture to be an issue with most lightweight shelters) and keep the mosquitos and other little critters outside where they belong. I slept in the Duo during an all-night rain storm in May, and stayed very snug and dry. With the outer zipper on one door unzipped partway (leaving the inner mesh door zipped entirely), I had no condensation problems. Gear has a space tucked beside either door, protected by the outer flaps.

Setting up the Specialist is as easy as you’d guess, considering it’s a very simple design. It does not stand on its own: the guy lines need to be staked. Spread out the shelter and stake it first, using the pre-measured loops to ensure they’re taut. Then enter the tent and attach the two poles. The pads where the poles rest are reinforced so you don’t have to fear a tear; if you’d rather use trekking poles to set up the tent, this comes in handy, as the tip of your pole rests on the reinforced material. This instructional video shows the trekking pole process very well.

There is are no less than six internal pocket compartments to store valuables inside the shelter. The guy lines which attach the stakes are advertised as reflective, so you won’t trip over them headed to nature’s bathroom at night, but I didn’t find this to be true. I tripped over them repeatedly!

Now for the size: in my experience, the Duo does not comfortably fit two people. You knew there had to be a sacrifice for that low weight somewhere, didn’t you? This fact comes as no surprise to me, as I’ve always reduced the capacity number by one for every tent ever made. Here’s how the math breaks down for the Duo: one regular-sized adult will take up 2/3 of the footprint space inside. Add a pad and sleeping bag, and maybe a pair of hiking boots protected from the elements, and you have a roomy shelter for one. If you leave gear outside and want to be very cozy, it will sleep two (somewhat overlapped). We tried it out with two adults (myself at 5’4″ and my husband at 6′ 2″, and while the Duo was long enough for him, it was too cramped in width. My eight-year-old and I fit fine, however, so one adult and one child will fit more comfortably. If you’re looking for a Solo shelter, I’d upgrade to the Duo and have lots of space for your stuff.

Overall, I was very pleased with this shelter. I didn’t experience any condensation problems, I had enough space for myself, I was never cold or wet on a cold and wet spring night, and it was easy to set up. The only downside: the Duo relies on staking and guy lines to erect. If you’re backpacking in very hard or rocky soil, you won’t be able erect the shelter unless you’re skilled in using natural anchors like rocks and roots, and even then, the lines have to be quite taut. If I knew I’d be camping out in rocky soil, I wouldn’t bring it.

The weight of the Specialist does not include the groundsheet, which is sold separately (or use one from your gear supply). The Duo comes in one color, a nice gray and yellow, and sells for just under $500 in most gear stores. Find it at Backcountry for $498 or Amazon for the same price.