i have been wearing this a lot. It is so warm it has been around -20C for several weeks now and this top keeps me really warm as a base layer without getting sweaty. not too hot not too cold perfect. not really used it iin warmer wheather, but great in winter.
They are not breathable, but if you open the zips on the upper leg it does let some of the moister out. Very good on cold wet days. Also work well as over trouser in the winter, when you don't want any heat to escape.
is this sized to be worn over layers for winter or is it a snug fit