I have to second 10K Cyclist's review. Found the same versus my merino bases. You can adjust the weight of your jersey to fit basically any condition with this base. Excellent at wicking sweat whereas merinos hold sweat at elbows, back of neck, glove junction. Can wear with Alpha ROS fly jacket (inner zip insulated liner covering torso) to upper 30's if still, 40's with wind, but if too windy, the Assos Ultraz base is excellent (and takes me down to mid to low 30's. Just a hint of itch when i put it on; once on, I do not notice it at all. If it was as soft as the Ultraz when i put it on it would be 5 star. As it is, my favorite non-heavy base.
Fits like a 2nd skin (6'5", 195lbs) - Size III (or ~XL). Amazingly comfortable under all of my long sleeve jerseys (light, medium & heavy). It's much thinner and lighter and fits me much better than either of the Smartwool Merino base layers I own. It also seems to wick away sweat far better than the Smartwool base layers. For a few dollars more than the Smartwool, it is worth it.
I've worn this under a thin long sleeve jersey & w/ a thin short sleeve jersey on top of that and been perfectly warm in temps in the low 40F range. With just a regular long sleeve jersey over this, I'm warm w/ temps in the 50's and well into the 60's without over-heating.
Cons: None.
