The Fast Stash tent from MSR is just barely a tent. The company calls it a “minimalist shelter,” and it can be set up with trekking poles to save weight on a backpacking trip.
Its design roots come from tarp setups where sheets of nylon are hung on cordage strung between trees. For the Fast Stash, you stake it out tight at all corners (the shelter is not freestanding) and then prop it up with poles that fit in corners under the awning on the outside.
At a weight just less than 3 pounds without poles, the Fast Stash is light but not “ultralight” in our book. (The included poles and stakes put the tent at about 4 pounds.) But for that weight you get ample interior space — 82 cubic feet, or enough to fit two big guys plus their gear.

During a weeklong trip in Alaska this summer, I lived out of the Fast Stash. Its single-wall construction was perfect on my stay, which included not a drop of rain. (Great for travel, not ideal for a gear test.)
Single-wall tents save on weight, but condensation is often an issue inside. We have read other reports on this tent that say the same for the Fast Stash — moisture will build up on the inside walls if the tent is sealed tight with people breathing inside, or during rainy or humid weather.
To remedy, MSR gave the tent ventilation on nearly all sides. Large mesh windows open up on either end. The door is huge and serves as another outlet.
A slight overhang above the door provides protection from water dripping inside. But in a gale this tent will not be as watertight as vestibule-equipped models.

As noted, the Fast Stash’s design is not freestanding. It’s critical to have solid stake placements. Setup is not difficult once you’re used to it, but it does require more effort than with a freestanding model.
Its shape is odd and boxy. This design gives great room inside, but it also presents a non-aerodynamic wall to wind. Make sure to consider wind direction when putting this shelter up in an exposed place.
The tent’s unusual shape includes a dramatically sloping wall and makes headroom an issue for whoever sleeps on the inside. There’s a wall right above your head if you sit up. It’s best to store gear toward the back and sleep close to the door.
A single door helps keep weight down, but that also requires that the camper on the inside step over the one closest to the door to exit. Nighttime bathroom breaks can be tricky.