impeccable Icebreaker quality - only a fit issue
I'm a small in all the Icebreaker t-shorts and long-sleeve shirts so i bought the bra in S as well. The quality of the bra is great - awesome stitching - but i was squished - so this had to go back. Medium works much better - I'm a 32C in regular bra. Hope this helps whoever is trying to figure out sizes.

Good serviceable bra
Love to run in wool, all year round. Great in cool weather, wore it today in 75 degree weather: nice. Snug getting on, snug getting off. Recommend this for a smaller frame. I am 5'4", 120 lbs., and had trouble with it. Very good looking, fit to be worn by itself. Looking forward to having it for a long time. Excited to have it. Love the black.

Fits very small
I have yet to test it but it fits very small. I normally wear an XS in the icebreaker line and the S was still too tight for comfort around the band. Reordered a M and although other reviewers say it was then a little too large, it fit me perfectly. The construction and fabric is similar to the other icebreaker clothing quality so I'm looking forward to a non sticking bra!

Part of the workout is getting into it
As a previous reviewer pointed out, this bra has an odd fit. I wear a 34B and find the band on the small is a bit tight, but it gives good support for running. It can be hard to get in and out of, but is worth the effort. I was concerned that it would chafe because the armholes seem to be cut for a narrower chest, but after a 4-mile race in 80+ temps, I can say that chafing is not a problem. No itch, no stink, dries quickly, and quickly wicks moisture to the outside so it can evaporate. Machine washes in cold water without shrinkage (I don't put it in the dryer). I'm happy with it and will order another.

Wanted to love it
I like the cut of this top. The armholes aren't too tight, the neckline is not too low or too high. The fabric is typical Icebreaker perfection. But the elastic band was too loose to keep the bra in place. I purchased a medium because I don't like to be squashed, but this top rode up if I shrugged my shoulders. It might work great for someone with a bigger ribcage than mine.