Any man who's been cold outdoors long enough has worked this out without being told: mittens beat gloves, every time, at the same thickness.
The reason is the air.
In a glove, each finger sits alone in its own narrow tube with its own surface area bleeding heat into the cold. In a mitten, four fingers share one pocket of trapped air and warm each other. Same material, same weight — a whole different result. It's the same principle as a down jacket, and it's why every serious cold-weather kit on earth ends in mittens, not gloves.
The catch has always been that a mitten turns your hand into an oven mitt. So men wear gloves, get cold, and blame themselves.
This is a mitten that opens.
Standing, walking, driving, waiting — closed, and you get the mitten's warmth. Something to do — flip it back and you've got a thumb and four fingertips. You are never wearing the wrong glove for what you're doing, because the glove changes instead of you.
And the fleece itself works the same way the lining of a good coat does: the pile holds a layer of still air against your skin, and it's the trapped air doing the insulating, not the thickness of the fabric. That's why these stay thin enough to close a full grip around a rail or a wheel:
"Because they're insulated they provide more warmth than typical gloves, yet they don't feel overly bulky, so I can still grip handles and stay agile." — Benjamin
Find the thumb, then feel the pile. That's the whole review.