arc'teryx is the best .... used to be a mountain hardwear fan, but arc'teryx has won me over....this jacket protected me on the Porcupine Rim trail in Moab and then packed into my camelbak when it warmed up.

A great pullover. Blocks about 90% of the wind and does pretty well with moisture. Keep in mind, it comes in a tight ergonomic fit, may want to try a size up just in case.

Arc'Teryx outerwear has become trendy in recent years, but they haven't gone the way of TNF...what I mean is that all of their clothing that I have owned/tried on is still very technical and high quality and not just for fashion. This shirt is no exception and will work great for the reasons I bought it. (spring/fall biking and hiking) Construction and materials are first rate and the medium fits like it was tailored for me. What you can't really see in the pics is the small zip pocket right above the left side hem...perfect for keys, credit card or anything else small. Since I knew the purpose of this shirt,(it is NOT a jacket or heavyweight pullover)and wasn't disappointed with any of the details.. I have to give this 5 stars. A little pricey for what it is, but this is a piece that will last years.

love this it stops ALOT of wind and is basically waterproof its got a smooth exterior and a mesh spiderweb-like interior that feels fine on bare skin. love it

This lightweight jacket/shirt is awesome to take the chill off in the morning. I love how well it breathes and how it feels against the skin. It's super light and comfortable. I think I could have gone for a Medium, but the Large is just dandy.

Made in China, but still an Arc'teryx piece. I'm using it for cycling and it did fine during my activities.

this shirt is EXTREMELY light -- like a windbreaker, but more insulating. it is perfect for a fall hike. i don't use it much for layering, because i prefer stretchier material for a greater range of movement.. also, the fabric is extremely durable -- a couple times i basically battled my way through dense foliage, and this shirt doesn't have a single snag. Oh, and one last thing -- it is super compressible -- you can compact it into a tiny roll about the size of.. say.. a large cup.

I love this layer. This is my goto layer for alpine/trad when the wind isn't kicking too much, and for cold weather aerobic workouts on most all days when a vest just won't do. I have yet to find any cons with this light layer, although it does not block the wind quite as well as the MH transition pull-over, but that is to be expected (the MH top is made with Windstopper).

The deep zip allows for adequate ventilation as well as helping put on and take off the layer easily.

The fit is athletic, but not overly snug, as the MH transition can be. I'm 5'7, 135, with a typical climber build, and the small fits me just perfectly.

There is only one small pocket that is sized well for keys.

Even though I already own this in size large, dark blue, I just now went ahead and ordered the white in XL (no white larges at the sale price). I'm getting a second one because I dig it that much. Great all around single layer for crisp hikes and biking here in the coastal range of Santa Barbara. It shields me from poison oak (as far as I can tell) and protects me from heavy chaparrel in tighter places when I'm mountain biking, especially on the single-track descents. I was gonna use it as a base-layer for skiing but it's a little too stiff. Wicks really well - which is surprising cause it definitely acts like a shield- altho it IS surprisingly warm for how thin it is. It's kind of like a mini-softshell in a way. Absolutely perfect for biking. Super well-made and I like the way it fits and looks on my lanky form. The collar is kind of formal, but kind of flattering too (or so I'm told). The cuffs look good too, altho they are light blue on mine, not white (as shown here). Everything I read in the reviews below is pretty accurate... it's worth it at the sale price, and it is a quality piece, despite not being made in Canada. It has found that good balance between being a protective softshell-like shield, but without the overheating when working hard, and it is actually pretty warm for how thin it is.... I guess that's just the nature of polyester. It's not super stretchy, but it does give a bit. I'm 6'2" 190, and the large fits me really well. I like the length of the arms because they keep me covered on downhills while I'm biking.

I bought this as a base layer for long hiking trips. I've worn it for multiple days without changing it and just as advertised, it didn't make me smell like my other base layer shirts. I don't find it wind proof, but wasn't expecting that from the reviews. A great piece of clothing.

i love this its awesome stops alot of wind and most water great base layer or top for early morning jogs

I'm giving this item three stars but that is more a reflection of my misunderstanding of what the Accelero's intended function is. I bought the Mercury Accelero as an insulating, sunlight reflecting, glacier walking, layer to wear on my trip to Rainier this June. It is an insulating layer only in the sense that any layer offers some degree of insulation.

It is very thin (but rather stiff) and more akin to a wind shirt in my opinion and is best suited as an external layer for cool (not cold) morning runs. It is cut a little large and you can't tuck it in because of a little credit card size pocket located right at the waist line. Nor can you can't cinch the bottom hem tight. Because of these reasons I found that cool breezes kept blowing up my backside freezing my arse off during times of light activity.

It is beautifully made however. I just haven't figured out how to use it other than as a high dollar wind breaker.

I purchased 2, the vermillion and deep blue. I am currently writing this from the Rustler Lodge, Alta, UT. It was warm today, 30-40s and I worked very hard in crud and am currently, "illegally" sipping on beer in the "business" center post-ski day. When I took off the accelero, I allowed my nose to inhale the pits of the shirt. Nothing, and I could smell my own pits (between us, I did the index finger swipe to the nose) and it was pure nast. The carbon fibers really do work!

I love this thing (just ordered a second)!

Very nice athletic cut, feels great next to the skin or as a light outer layer for cool days. The quality is exceptional... everything from stitching to materials to zipper smoothness.

The pocket is small and pretty useless for anything beyond a gel pack, credit card or key. I'd really love to see a version of this with light weight hand warmer style pockets (a place to keep my paws out of the wind and to stash the dog's leash while he's running free).

This piece further cements my addiction to Arc'Teryx (whether made in North America or Asia).

i love this pullover as a mid layer for cold or outer layer for cool weather hiking. i can't say enough good things about it. 3/4 zip vent provides great temp control.
it's breathable and even blocks wind (a little).
people complain the arc'teryx has gone downhill since not manufacturing in canada anymore, that's crap. this is a fantastic layering piece. seriously.

As with all arc'teryx items it is well made. However, it is not what I want out of a garment. It is somewhat warm yet fairly thin to wear as a single layer. It would layer well under a jacket, but why not just buy a warm under-layer? I returned mine and did just that.