The Ion Windshirt, while on the Appalachian Trail provided great wind and rain protection. Not recommended for a heavy downpour, but in lighter rain conditions and brutal wind the shirt was perfect. It cinched down tight not to flop around and be annoying. Good product, recommended for those trail runs in the mountains when a little extra protection is needed when the thunderstorms roll in.

I used the windshirt this past two months on the Appalachian Trail and found it to work great. It's a water resistant shell, that in mildly wet weather, repels the H20. Not recommended for soaking rains, unless their brief ones. This windshirt dries super fast, and even when wet, will keep in warmth. It sinched down tight when needed instead of flapping all over the place. Good product!

Ion is a great wind & light rain jacket. Definitely for the active sports of running, hi-tempo riding, & XC skiing. Don't try & sit in it at a December Chicago Bears game. I'm 5'10" & ~ 165lbs, it has a technical fit, but never feels restrictive. My Men's medium weighs 4oz. For those windy days or rides, its a very versatile piece when you choose to layer it w/ various weights of wicking base layer. I found mid 50's w/ capilene 2, 40s w/ capilene 3, & powerstretch for the 20-30s to work best for me. I know its cliche, but it really does work & keep the wind out w/ its tight weave. It moves body moisture well, haven't had condensate on the inside at all. Haven't had long enough for durability issues, but I wouldn't run into thorn & bramble patch with it, nor would I rock climb in it. Has a soft hand, drapes well, matte color (not shiny) packs into its chest pocket, tech fit eliminates need for waist cinch cord, has longer tail, has funky foam hood drawcord (keep wgt down?), hood rolls inward to become part of collar w/ strap that snaps. If you already own tons of various weight baselayers, this maybe right to keep winds off, but if you already own Marmot DriClime jacket/wind shirt this may be a redundant piece.

Sweet. I love this thing, although mine is without hood... Great for the cool morning trails in Ithaca, NY. It's surprisingly quiet too, which I value in running apparel. Words.

while i was impressed with the wind-stopping capabilities of this ultra-lightweight windshirt, the fit leaves much to be desired. i like an athletic fit and smalls usually fit me just right (at 5'9" 140lb). the sleeve length was fine but the torso circumference felt too big.

with no cinch around the bottom (waist) of the jacket and a rather short fit that leaves my mid-section exposed when my shoulders are at all raised, water and wind soon both found their way in.

i will be looking for something with a slightly longer/slimmer fit and a cinchable waist.

I have 2 Ions. Both in men's size Large.

One is the original Pertex version. It weighs 3.155 oz. on my digital scales. It breathes very, very well. I wear it over a merino wool or poly shirt typically. It has been great over the years. I leave it in my pack as one of the 10 essentials. I've used it in the Andes, Rockies and Blue Ridge while hiking, cycling, sailing and paddling.

The other Ion is newer, 2006. I had a Pertex tag, but I think they started using a different DWR because it doesn't breathe as well as the original. It does resist water for longer. It weighs 3.327 oz. on my scales.

You weight weenies need to get a life. Variations in the DWR coating, fabric and what not, though within manufacturing tolerances, can explain the weight difference. If you want it to weigh less, cut off the metal zipper tabs and use cord instead. Dental floss would be lighter.

Having featherweight gear where you want it, when you want it often spells the difference between failure and success. That is where the Ion Windshirt fits in. Wind resistant, water repellent, and breathable, the Marmot Ion Windshirt is not just another wind breaker. It is a major breakthrough in wind-resistant garment technology. Functional, practical, and nearly weightless, the Ion Windshirt shelters you from just about anything short of a hurricane.

Top reasons the Marmot Ion Windshirt rocks -
Efficient when the wind howls
Hooded for added protection
Easy zip on/zip off vs. pullovers
Lightweight
Stashable
Additional notes –
Keep in mind it’s designed for wind not rain. Putting gels in the front pocket caused some annoying bouncing, pocket on back or side would be better. After significant wear cuffs lost elasticity, both aren’t a big deal with all you get for the price.

I have now worn this windshirt running, mountain biking and backcountry skiing and it has performed better than I had dared hope in all three areas. It's light, has a reasonably athletic cut, a reliable zipper, a roomy hood and has been extremely effective as a wind-shirt not to mention doing a surprisingly good job of shedding light snow during two recent ski tours. To tell you the truth, I had assumed the Ion would do a good job of keeping the wind off but what had concerned me was its breathability. So far I could not be more pleased. it has stayed remarkably dry on several sweaty uphill runs, two uphill bike rides and a long ski climb on a windy but sunny day. Exactly what I had hoped for. I wish I'd picked another color (black is so -- well, drab) but otherwise a total score.

I bought this on clearance as a temporary wind jacket and haven't bought one since. I bought it because it fit and it was cheap, and when I only when I got it home did I realize that it's a men's item, not a women's, if that gives you an idea of torso room.
My only gripes about this item are the length and the hood pulls. It's a little short for more than casual wear, pulling up with arm movement, thus lessening it's effectiveness. I have a little bit of a hard time keeping the hood pulls in a tight position. They gradually slide loose, making for an irritating and sudden exposure to the elements. Other than that, it's a great item!

I have to say that I am amazed by how warm this shell is for how light it is. I wore it with only a under-armor turtle-neck for a long run in snow and wind, when the temp got down to around 7 degrees and I stayed nice and toasty (of course I was moving).

Great combination of light weight and warmth. Good for holding in warmth and cutting the wind at low exertion times. It doesn't breathe quite well enough for high exertion activity.

Lightweight, waterproof, windproof and easy to fold up and put in your pocket.

It doesn't weigh much, it won't shed a downpour, but it is great for layering, cuts wind well and looks great!

Love wearing this on a cooler,windier day.Keeps the rain away and yet keeps me warm....specially on a bike.Light wearing and folds up real small.Kinda weird tho....I'm 5'11"/170#/chest 42"... the sleeves are more than long enough and the chest has the room.....however the length is kinda short.Not overly but it is short.Blue is the colour.......is darker than the pic!

I have more gear than I should, but I could not restrain myself. After buying one on sale for my wife, I had to add this wind jacket to my gear list. At only 5 oz with hood, this has quickly become my favorite.

I was giddy at the idea that a hooded jacket could be 3 ounces- but ounce counters and gram freaks beware!
I have a Men's SMALL and my brand new calibrated scale measures it at 4.7
the construction is ok, but no drawstring at the waist and the drawstring keepers at the hood are flimsy foam that wont last. Should have used mini-mini cordlocks. Bottom Line: if you are going to advertise a weight, at least weigh the item.

I bought this jacket for my husband and he absolutely loves it! Great for long backpacking trips with limited space in your pack and questionable weather.
Only problem: he normally wears a medium in clothing, but it was a little snug and short in the front, so we had to return it for a large.

I was looking for the lightest wind jacket I could find. The men's large actually weighs 5.2 oz, not the 3 oz advertised. May sound small, but if every item were off by this much, a "10 pound" pack would really weigh over 17 pounds.

I purchased this wind jacket to replace my older worn wind Jacket. It to was a Marmot model which other then the color is the same as the new model. The material is a little different as well. It feels thicker and heavier. This is a nice jacket but don't believe the 3.0 ounce listed weight. I weighed mine (men's size Medium) it came in at 4.5 ounces. My old model was 3.0 ounces. I think Marmot needs to update their weight listing on this item?