You know me, I like to wear stuff for a good long while before I review it, but this lovely soft thing has passed all tests of endurance. I've worn it in all sorts of weather, too-- ranging from +100 degreeF temps with +80% humidity all the way down to weather in the 40s. (Yes, indoors, but we don't use AC or heat.) I've worn this for nogi as well as under a gi, but most of my wear was under a gi.
I'm 5'2" 135 lbs, and I wear a small. The sleeves and torso are long enough that this could fit someone longer/taller than I with ease.. at least an extra 2-3" in each. These rashies are made of bamboo-viscose which is touted as a more ecologically-friendly textile, as well as absorbing more sweat. This seemed kind of unique to me-- unlike most rashguards which are made with a nonabsorbent material like polyester, the bamboo did seem to retain more water and left smaller pools on the mat when training nogi.
Pros: the best thing about this rashie, to me, is the texture. Soft, soft, soft! Fuzzy and comfortable and stretchy. When I first put it on in warm weather, it feels a bit too warm, but I did not feel overheated while rolling. I also like the design-- which is available in ranked colors-- because it looks kind of like a rugby jersey. Surprisingly, the stitching connecting the black parts to the white parts was not too tight or restrictive or scratchy. The neckline is not too small (usually I am not a fan of crew necks) and the bottom hem stays tucked into gi pants if that's where you want it. If you leave it out of your pants, it doesn't ride up like crazy, either.
(Excuse the scraggledy hair and post-training face of fatigue.)
The branding is appealing-- a small circular logo over your heart, and a larger name logo vertically along your ribcage on the right side, under your arm. But it is printed straight onto the material, which usually ends up cracking and peeling over time. Still, in the six months I've worn this, I haven't seen peeling and only a small amount of cracking.
The red contrast seaming is subtle but aesthetically pleasing.
Cons: This fabric shows wear. I don't think it's actually getting thinner or abraded in any fashion that would impair its utility, but it looks "pilly" and rubbed. (The color has stayed a nice even black, so any fading you see in the photos is just an artifact of flash photography.)
Also, this sucker feels warm when you first put it on. As I mentioned, while you're training you'll feel fine... but hanging out waiting for class to start will be toasty. If it's temperate or even chilly weather, you'll enjoy it. If it's hot, well, you will be slightly warmer on a subjective basis (but then again, you might not choose to wear a long sleeve rashie under a gi when it's really hot!)
In summary, this is a quality product and something a little different from all the rest of the rashies on the market. I think it would make a nice holiday gift for the grappler in your life who already would seem to have all the rashies they could use.