Wore these tights under my Mountain Hardwear Makalu pants during my summit attempt of Mt. Rainier and stayed toasty the way up and the way down. Smooth finish moves easily under layers. Tights are very high waisted which is better than riding at the top of your crack but I ended up rolling them down a couple of waist bands worth. And because they are kind of slick you'll definitely need a belt for your pants. Otherwise your pack's waistbelt will give you that undesirable "jailing" "gang banger" effect. All in all a very effective base layer.

Wore the Bird Head Beanie on my summit attempt of Mt. Rainier and was completely satisfied. I have a normal size dude's head and wore this comfortably under my climbing helmet. Head and ears never got cold. The beanie pulled down comfortably to fully cover my ears and the back of my head to below my hairline. I hate beanies that leave that gap between it and the collar. No problems here.

I'm giving this item three stars but that is more a reflection of my misunderstanding of what the Accelero's intended function is. I bought the Mercury Accelero as an insulating, sunlight reflecting, glacier walking, layer to wear on my trip to Rainier this June. It is an insulating layer only in the sense that any layer offers some degree of insulation.

It is very thin (but rather stiff) and more akin to a wind shirt in my opinion and is best suited as an external layer for cool (not cold) morning runs. It is cut a little large and you can't tuck it in because of a little credit card size pocket located right at the waist line. Nor can you can't cinch the bottom hem tight. Because of these reasons I found that cool breezes kept blowing up my backside freezing my arse off during times of light activity.

It is beautifully made however. I just haven't figured out how to use it other than as a high dollar wind breaker.