Avoid. Windstopper doesn't breathe worth spit for active sports like skiing, hiking or jogging.
I own this hat, M.H.'s Micro Dome, and an uninsulated OR Windstopper skullcap, and never wear them, because I own two vastly superior "Windpro Hardface" hats (one by Outdoor Research and one by REI).
Wind Pro Hardface sheds water better than any fleece, and ounce-for-ounce my OR & REI Windpro hats offer all of the warmth, comparable windproofness, and breathability several orders of magnitude better than any Windstopper fabric.
Don't believe the Gore hype machine.
A hat like this may be fine for standing around, or for casual wear by folks who simply don't sweat, but once you've tried a *real* breathable fabric like Wind Pro Hardface you'll never go back.

Avoid. Windstopper doesn't breathe worth spit for active sports like skiing, hiking or jogging.
I own this & M.Hardwear's Dome Perignon, and never wear them, because I own two vastly superior "Windpro Hardface" hats (one by Outdoor Research and one by REI).
Windpro hardface sheds water better than any fleece, and ounce-for-ounce my OR & REI hats offer all of the warmth, comparable windproofness, and breathability several orders of magnitude better than any Windstopper fabric.
Don't believe the Gore hype machine.
A hat like this may be fine for standing around, or for casual wear by folks who simply don't sweat, but once you've tried a *real* breathable fabric like Windpro you'll never go back.

While the review of Dec 19 is helpful in that indicates the widths of Zipp bars are measured Outside-Outside (BackCo take note: specs like this simply MUST be included in the item listing itself), the rest of the listing is incorrect.

The de-facto industry standard for handlebar widths is Center-to-Center in centimeters. While some manufacturers such as Zipp measure Outside-to-Outside, there is NO SUCH THING as nominal handlebar widths measured Inside-to-Inside.

Why does this matter? Because an Easton bar with a nominal 42cm C-C width will be the same width as a Zipp bar with a nominal width of 44.5cm O-O.

While nominal widths are a good starting point, the only surefire way to make sure you are getting the width you need is with actual measurements.

As for the Nov 20 review by a 220 lb "clydesdale" who rides an Orbea Orca and is concerned with stiffness: keep this fact in mind: the ORCA is one of the flexiest carbon frames ever made, especially at the head tube junction.
I've ridden the bike, and the type of bar is almost irrelevant: so much flex comes from the frame and fork steerer, steering will never be precise, especially for a larger rider.
A rider this heavy shouldn't be on a frameset that soft, and probably shouldn't be on a 185g carbon bar either, for that matter.
Cum grano salis, indeed.

Apples to apples: compare this Marmot piece to other powerstretch tops on the market (e.g. Mtn Hardware's best-in-class Powerstretch Zip T), and you'll notice right away that this is NOT A PERFORMANCE FIT item.
Granted fit will vary based on your build & sizing choice:
I am 6'1", 165 lbs, with a 35" sleeve length, and I had to go with the L to get the wrist coverage I needed.
Even with the Medium I tried, however, the torso cut was roomy & the hem length is unusually long: Marmot has taken a traditional base-layer fabric and given it a mid-layer jacket design with full-length zip and hand pockets, and the end result is a very Cloudveil-like, roomy, new-school fit.
Don't expect too much of this piece as a stand-alone jacket: powerstretch isn't designed for abrasion resistance, offers little wind-resistance, and pills much more quickly, say than Polartec's beefier Windpro hardface fleece.
Where I do agree with the previous reviewer: this piece is amazingly comfortable. It excels over a t-shirt as a breathable spring/fall travel layer, or over your base layer and under a shell for colder days where the base layer alone just isn't quite warm enough.

Finally a Zip-T-Neck that doesn't look like underwear, and doesn't bind under fleece and softshells!

I have two of these, and often wear them casually on their own. The cut is roomy enough, from the neck to the sleeves, to wear even an expedition-weight T-neck underneath.

Garments' only weakness: why not add a tongue beneath the zipper in the neck area? No one likes a cold zipper on bare skin!