Part Halloween costume, part base layer, 100% awesome.
I've had the 1 piece Ninja Suit for the past 2 years now and I'm never going back to separate base layering. I have the non-merino wool version and it does stellar. Smells a tad more than the merino would after multiple days on hill (merino is antimicrobial, yea thats science bitch ) but I can't complain. Here's why:
-350 degree zipper lets you defecate and urinate without getting out of the suit
-it wicks moisture extremely well, leaving you dry which translates to warmth so you can stay out longer
-thumbholes keep unwanted drafts out and your hands warmer
-built in hood is fantastic for keeping your noggin warm when the Polar Vortex is around but is good for spring days when you don't want a facemask on
-I would suggest sizing down one for a snugger fit
-did I mention it has a cool 350 degree zipper?