I've used this pack exclusively for the last 2.5 years for virtually everything outdoors: alpine, rock, and ice climbing, alpine and XC skiing, hiking, camping, and even mountain biking. It is very well designed.

I've found it to carry almost anything, on any length trip. In emergencies, I've stuck four ice tools in the tool holders, two pairs of skis and poles in the side loops, and two 60m ropes under the lid. Straps on the front and top of the pack expand its capacity further.

Stripping the lid and cinching the buckles pulls the almost-empty pack into your back with enough structure to hold skis. With the spindrift collar up, I can get 50+L in. Daisy chains on the front and top allow strapping of even more gear (snowshoes, foam pads, bear canisters, etc.). It holds tiny loads well too; I've completely stripped the pack (hip belt, frame, lid, buckles) several times for light day trips (a cool feature is the rope-buckle and crampon-buckle can be clipped together to pull the top in more).

I used the pack on a 6-day glacier traverse during the summer where we summited 6 peaks. I was carrying the majority of group gear, including tent, stove, fuel, shovel, and rope. With the rope outside, everything else (rock, glacier, and camping gear; food, water, and luxuries) fit inside, with plenty of room for more. For summits, I fashioned a smaller pack out of the lid and a 0.5" sling where I could stuff my hydration bladder, energy bars, and extra clothes. It does well in the winter too.

It carries 0-45lb loads great. 50lbs is pushing it. I've carried 70+lbs with the pack, but most of this ended up on my shoulders. It has a single, flat stay down the middle of the frame which buckles under heavy loads.

Improvements: I've been exceptionally harsh on the pack, but the fabric coating started to disintegrate after a year (although this seems mostly to be aesthetic); as such, it is no longer water resistant. A tube-style stay would be a lot stronger and hold a lot more weight. The gear loops on the hip belt are superfluous; 99% of the time I clip something to my hip, I'm wearing my harness.

After much research, I purchased some of these to replace my heavy, bulky Petzl Attache lockers. First off, I would be lying if I said their totally badass design didn't influence my purchase. Now, on to reviewing...

Strength-wise they are on-par with the Attaches, give or take a kilonewton. However, they are almost half the weight. The specs really don't give Mammut enough credit for how light these are. At 58g (verified), they are lighter than many of my non-locking carabiners. I love watching the stunned expressions on my friends' faces when they feel how nutty light they are.

Both the nose and carabiner body are significantly narrower than on the Attache. I found this made them easier to clip, especially when clipping anchor chains on sport routes. The gate requires more force to open than the Attaches, but is easy to hold open, and snaps shut sharply when released. It does not chafe against the nose at all, even after use and cross-loading (which is difficult to do with the carabiner shape). Operating the locking sheath remains silky smooth, even after repeated use at dusty crags.

The only downside? The gate opening is pathetically small... about 1cm less than the Attaches. However, for racking slings or pulleys, tying knots, or building anchors, it is plenty wide enough.

I bought the O-Wall over other ovals (such as the BD Oval) because of the keylock gate. The keylock gate works great, the biner has a great narrow nose which fits well through small holes, and a very clean design. However, I have two gripes with it: it is heavier than every other oval on the market, and it isn't even oval! It's an oval-ish D-shape. This poses a problem when using it with pulleys like the Petzl Ultralegere which need to sit parallel to the carabiner's spine. A problem when using it for a hauling or rescue system.

Purchased this as an alternative to my heavy-weight TNF Windwall fleece. It is easily as warm, but is less bulky, weighs nothing and packs to the size of a tennis ball. I layer it over a lightweight shirt and under my soft shell. It has kept me comfortably warm sitting on summits at sub-zero temperatures in heavy wind. I'm 5'10" 165lbs and ordered a medium. Fit is a little baggier than I was expecting, but torso and sleeve length are both long enough to retain coverage during high reaches. As an "ultralight" garment, you have to accept the decreased durability. I'm cautious to wear it as my outer-most layer, and the collar lining is showing wear. That being said, I would highly recommend it.