Robert S.wrote a review of Marmot Expedition Mitten - Men's on March 8, 2017
Fit: True to size
Primaloft Gold is the best synthetic insulation, and these have it. These are not over-padded, so the dexterity is good for mittens. The fabric is great. The fit is great. It has a nose-wipe. It has one-handed draw-strings. I can't imagine better unless you wanted a removable liner., in which case there is the OR or the Marmot 8000.
Some people say these run large. I have a size 8 hand, and ordered a medium. I am 5'8 and 144 lbs and do not have large hands. They fit me perfectly, so I claim these do not run large, but are true to size. My OR Adrenaline mittens ran small, and I had to get large in those. The OR large is like these Marmot in medium.
I am able to comfortably wear Thermasilk or Serius liners in them, but my not very thick Black Diamond fleece gloves won't fit in. If I wanted to wear real gloves inside them, I could have ordered a size up.
I used my thermal camera and put ice blocks inside these (see photo on the right), the OR Adrenaline (middle), and Marmot gloves (left). These had significantly less cold transmission.