I've been using these wind shirts for a while now, with one of them having hundreds of days of use on it, without issue.

If you're wondering why the strange title, this is actually poking fun at their own marketing material, which clearly states their wind shirt "refuses to be sultry" :)

Associated PICS for this review: HERE

The quick TL;DR rundown list:

• Around 20 freedom-quid on Amazon. Possibly the cheapest windshirt around.
• 2.7 oz in XXL after mods.
• High CFM of 50 which equals great breathability.
• Folds into own chest pocket.
• Hooded, but the hood is not adjustable and might be ill-fitted for some users.
• Sizes are Asian sizes, so go up 1-2 sizes for American sizes. I usually wear L or XL, and went with XXL Dooy. EDIT: There seems to be some contention over sizing up in comments, so, I don't know for certain now. :)
• Excellent if you already have a rain shell, not enough if it's all you have against cold wind.
• Proprietary fabric that looks really cool in how it is dimpled. Also very silent and smooth under pack straps.
• No DWR! It's kind of useless these days anyway, so why bother paying for extra chemicals on your clothes?
• Packs into own chest pocket. Chest pocket holds a iPhone 13 mini, just barely. Larger phones might be too big.

In total, I have owned 3 of these. One has several hundred days of use on it, and one has a few dozen, and one was given away nearly new. None of them have shown any quality control issues, nor have they been babied at all.

Fit:

I would say these are an athletic fit, which wouldn't accommodate people with wide torsos or arms as easily. But, for those it does fit, this reduces weight and chaff. They also run small, as some Asian-sized clothes are for people in the west. So go up 1, maybe 2, sizes right off the bat.

Performance:

This is where these wind shirts really stand out. High CFM rating of 50 is excellent for preventing sweat build up when cranking out hard miles, but also while blocking out just enough wind to keep a bit more warm. This can be a negative feature though if you only have the wind shirt and no rain shell. The high 50 CFM airflow rating will fail to keep you warm on a peak in cold winds. If you only carry one jacket/windshirt you should use a rain shell alone or a low-CFM windshell with strong DWR.

I also took to now using TWO wind shirts when I am outdoors. That way I can gain a step between wind shirt and rain shell for more control over more specific conditions. The two of them layered on each other holds more heat than a single layer with the same, net CFM rating. Having the two wind layers on top feels more like a thin thermal layer was also added, due to the trapped air pockets.

Durability:

All of my zippers have held up fine. Some reviews mention failed zippers. Being such a cheap jacket, there are probably some out there with defective zippers. If yours are not defective, then they will last just as long as any other UL zipper. One of my wind shirts has likely had the zipper up and down over a thousand times by now without issue. The fabric is also holding up great! No holes or pulls, even after bushwhacking a lot.

MODS:

1. Cut out the extra neck storage area used for the hood. And get rid of the velcro patches that hold it together. It's added weight and pretty useless.
2. Add zipper pulls! I used some leftover UL guyline cord from Zpacks. The zippers are tiny, and pulls make it way easier to grab.
3. Cut the flap away from the chest pocket zipper. The flap covering it does nothing more than get caught in the zipper from time to time. Just cut it out.
4. BUY A PAIR OF GINGHER SCISSORS! They are pretty much the best scissors in the world for cutting fabrics. They are insanely sharp, like cutting with razor blades. Really helpful item for UL people cutting junk off their gear.

Purchasing:

I don't know where these can be purchased other than Amazon. I hate to post a link to Amazon, but if you search for Dooy wind sun shirt, you will find "Dooy Sun Protection Jacket Ultra Light Thin Breathable Packable Outdoor Cycling Jacket Hoodie Skin Clothing for Men & Women "

Maybe someone can post a link to other places to buy these? Thanks!