I'm typically on the top end of Large but I go with XL most of the time with BC.com products. In the case of the primaloft, the XL was a tab long in the waist and also in the arms. I;m about 5'11 190. I have not tried the Large yet because they're out. I'm worried that I will be in between sizes with this product.

This jacket is wonderful. It is super lightweight and warm, which in Minneapolis, people appreciate. I bought this jacket to replace my down puffy parka for around town, which was actually too warm for me. The primaloft is less bulky than down and keeps me the perfect temperature. Hood is great and styling is subtle The only complaint I have is the non-adjustable sleeves that you cannot tighten. This jacket is great to rock the town on.

Love the backcountry.com brand, so far the quality seems A1.
Oh ya, the goat logo drives the girls wild!

I got this just last week and I have to say, another great piece of gear from BC. The wool blend did great in the light rain and I'm plenty warm up in the mountains. I love my Shift (last years model) but to be honest, it gets too warm sometimes, especially when the sun hits it. The Siphon is the perfect light jacket. The pocket lining keeps the hands nice and warm, too. The chest pocket will hold maybe and ID or and Ipod.
BC stuff is very stylish - I got comments about ten mins after I left the building wearing the Siphon. I am 5 9 , 165 with a 42R chest - literally the average American males' size- and the large fits me like it has been tailored. BC stuff is snug, and the arms tend to be on the long side. I'm not trying to sound concending when I say that if you are rocking a beer belly, I can't imagine this jacket would look good on you. It is now my go to jacket, and I think I'm going to buy one for a friend.

This is a great go to jacket for winter in new england. It blocks wind and has enough insulation so you can throw it on top of a t-shirt on all but the coldest days. But it is still thin and light and doesn't feel bulky (I can play disc golf in it without problems). It is low key enough to wear around town but works fine for lift accessed skiing. In extreme cold or rain or for serious aerobic activities I wouldn't use it, but 4 of 5 days it gets the job done.

Zipped up all the way, the collar can be a little restrictive if any of your base layers have collars sticking up.

I'm 5-7, 155lb and a medium fits great with enough space to toss a couple layers underneath and still maintain a good cut.

I love having a primaloft jacket like the Siphon. I owned the Patagonia Micro Puff hooded jacket for a few years until I lost it and I decided to try a cheaper version when replacing it. These jackets are really warm, basically windproof, thin, and light. The exterior material on the Siphon is a bit thicker and tougher than the Micro Puff, which is a good thing for me, since I tend to push the limits of the jacket's intended use by wearing it snowboarding in the trees, etc... This jacket will rip if snagged, but I have no problem using a gore-tex patch.

My one problem with the jacket is that a seam on the inside of the jacket started pulling apart within the first week or two of everyday street use. I haven't given it any hardcore camping, snowboarding, etc... testing yet, but I am already skeptical of it's long-term durability given the clear weakness of the stitching. For urban use, this jacket is a no brainer. If you tend to push your gear and rough it up, you may want a more time-tested brand, especially one with a lifetime guarantee on seams, zippers, etc...

Got this back in november and have worn it daily. I get a ton of compliments from normal pple to gear heads at least weekly. Quite wind resistant and warm, I can wear just a t-shirt and be good down to 20 degrees. I also bring it winter hiking as a back up in case i get cold. It layers over and under stuff great. I am 220 6ft and a large fits snug but enough room for a baselayer and my rime pullover underneath. It definately lacks a few technical features (like wider forearms and wrist closures), but it is a great cross between technical and casual and looks great to boot.

This jacket is a good fit. I have long arms and the sleeve lengths don't make it look too young on me when reaching across the bar for a beer. I've worn this in temps from 20 to 50 and it is great...at 20 degrees and windy, I feel no chill with short sleeves. It is definitely windproof, stylee and warm, but not sweaty like your NF bubbles.

Super lightweight. Worth the cash.

The Siphon is a great jacket for cruising around town in. Even on the coldest nights, the Siphon kept me warm with only a t shirt on. I love the only down side is that it fits a little small. I wear a medium and went with the large which fits great. I recommend this jacket for all!

I'm a SoCal guy but this last week has been in the 40s and windy rainy conditions. Love this jacket. I wear a large and I'm 6ft 165lbs. Perfect, simple design. Nice. Thanks Backcountry.

i'm 6'3 185lbs with long arms and the large fits perfect...quality jacket...like others said....quite warm, protects against wind, and is very thin/light....proably wouldn't wear skiing

This jacket has become my favorite for just about everything. It's great for kicking around town or the backcountry. It is very light weight, but still packs the heat. If it gets below 20F I'll wear a long sleeved shirt under it. Fleece lining in the pockets keep the hands toasty. It has an athletic cut, fits like Arcteryx jackets. I'm 6'4" 210 and the XL fits great. The arms on this jacket are a little long and the chest pocket is pretty small. However I HIGHLY RECOMMEND this jacket.

I am 6'2" and 225 lb. The XL fits snug but not uncomfortable. Cannot layer underneath but it fits well under a shell. Arms are 1" long (and I have long arms) with loose cuffs, so I sewed cuff closures on. Also, the hood does not have a strap or pulls to adjust back and it falls forward. A strap with a fastlock sewed on the back took care of the problem. The breast pocket is a little small as well. Otherwise a good jacket to layer under a shell.

this jacket is incredibly warm for how light it is. It not bulky and fits great. It is very water repellant. Holding it under the sink shed all water. I wear it everywhere in the winter.

Picked this up to wear around town and it's great for that. Worn it in temps from 45 down to 15 and been good to go with just a cotton t-shirt underneath. Also, stops wind DEAD, and stays dry even in a downpour. I've worn it skiing too, was more than warm enough in the single digits at killington with a t-shirt and midweight polypro. Not sure I'd trust the outside material to not rip if I were to have a close encounter in the trees, but I don't think it was ever meant for that, so this thing is stellar. I'm 6'2" 205 and the large fits great as an athletic fit.

This jacket is the one I always grab when I'm just stepping out of the house and it's 30-40 degrees. It's insulated, it's pretty waterproof, blocks wind nicely, and let's be honest just looks good. It holds up great in the snow too, I wore it christmas tree picking in a blizzard and stayed warm and dry. It doesn't breath as well as a hardshell, but that's not what it's designed for. The cut is athletic with really long arms, so you less lanky folk might want a different brand. I get complements on this jacket all the time. Even my girlfriend likes this jacket. Pick one up.

this is one of the best jackets i have ever owned its warm and is amazingly comfy and nice but i would not recommend it for someone looking for a skiing jacket its not the most wind proof or waterproof you'll want a thicker shell

Just got this in the mail yesterday...Super light weight, but very warm. I was surprised how much warmer it was than I had thought. For $70 on steepandcheap.com, buy one in every color. As said below, fit is amazing and its extremely water repellant. I held the sleeve under running water and it shed every drop, no residual moisture.

This is a pretty sweet jacket......it has nice styling and great fit. I'm 6'1" 175 lbs and the large couldn't fit me better. It's lightweight yet warm, and will be great for layering. I now have two jackets from this company: this one and the hooded wool jacket, and I wish I could buy them all.

Bought this sucker on steepandcheap for 79!!! Such an awesome jacket for around town. Small hugs close to my 5'8" 150lb body. I'm a sissy when it comes to cold weather, but this thing keeps you sooo warm. And the best part is it's super thin and light. Can throw it in my bag when the mercury goes up again. BUY IT!!!

It was 15 degrees out with 30 MPH winds and a HEAVY snowfall, and I only wore this jacket and a T-shirt underneath and was warm and toasty inside. I could be out for hours and have no problem. I swear by this jacket. The hood closes up well. The insulated hand pockets are nice. The only annoyance is that breath condensation builds up along the mouth area on the hood.

The Siphon is my new favorite jacket. As others have noted, it's quite warm in 30-40 degrees with just a t-shirt underneath. It's pretty versatile too - fits well enough under a soft shell for skiing or is great on its own on a night out to the bar.

I'm 6ft, 170lbs, which usually puts me frustratingly between a medium and large on just about all outdoor gear. The medium fit is near perfect.

This jacket has gone with me on some pretty chilly adventures and is my definite all around go to jacket. I used it for some late fall backpacking and I will definitely be using it again-the packability is pretty good and comfort was worth it. Layered with a 260 weight Icebreaker turtleneck I was comfortable in temperatures in the teens. I wear it around town and get compliments on how good the jacket looks. So if you want to shred the gnar of utah, chill out in nor cal and stay sexy the whole time--Get this jacket!

The Backcountry.com Siphon Primaloft Hooded Jacket is a great alternative to lugging around a bulky jacket. The primaloft interior keeps the warmth in without making you feel like you're wearing a jacket ready for the Arctic. It's comfortable and lofty and also works as a great mid layer underneath a shell.

This has very quickly become my go-to jacket (no small feat for a jacket whore like myself). It fits well, is plenty warm for all but the coldest days, and seems pretty durable so far.

Living in Utah, this jacket is a godsend. I can wear it with just a T shirt in up to 30 degree temps, anything more than that and I put on a light baselayer and I am good down to 20 degrees. With my merino baselayer and Rime pullover, this jacket is good for near 0 degrees. Is INCREDIBLY light, far lighter than my TNF redpoint optimus, which I quickly sold in favor of this jacket. My only gripe is the lack of a windflap (although I have never felt a gust, it would be good to have) and the lack of an INNER pocket. The fit is amazing, as is the stretch properties of the fabric. its made with Primaloft Sport LM, a lower loft version of Primaloft One. This jacket is really something special. The styling is great, as is the fit and weight. Its my go-to jacket for everything casual between 10-50 degrees. Perfect for fall nights, winter and cool spring days.

When partying on the back deck on a cold Utah weekend night in the winter, this is the jacket you want to be wearing. Super stylish and as warm as you need it to be. Extremely light and comfortable and stays cool when wearing outdoors. This jacket is a must have!

This product description sounds like something out of the recently bombed republican bid. Why try to sell a good product based on an us-and-them-higher-than-thou philosophy? As peddlers of lots of "over teched alpine assault" gear to many people who are probably "retro geezers" and "tourist-trons" you should remember that we are all out there together. As a long time instructor and guide I have to encourage us all to share the high vibe and not get all judgmental. Maybe West Valley Utah has been overrun by "faux locals", what a great opportunity to show them how to go big. Have fun.