These mittens are made from the same windproof, water resistant fabric and engineered polymer (a specialized open cell polyurethane foam) that is used in the other clothing that we make.
These mittens have a textured, rubberized, heavy-duty fabric on the palms that allows for more rugged work.
The insulation and fabric combination allow warmth even if soaked through. I have taken mine and submerged them (with my hands in them) in water when the outside temperature was 15°F, took them off, wrung them out, and put them back on my hands. Within 30 seconds my hands were warm. I’ve done this multiple times under various conditions and have had the same positive result.
The mittens are part of the system, and it must be remembered that keeping your core warm is critical to keeping the extremities warm, because your personal source of heat is in your core.