This is a very rare Marine Aircraft Group / Marine Aircraft Repair winter hat. To be perfectly honest, there is a chance that the M.A.G. and M.A.R. initials stand for something else as I have not been able to find other examples of this hat during my research. As you can see from the photos, some of the fur is missing and there is a small tear in the front of the hat at the seam just below the sergeant print. These are the stamps on the hat: Sergeant rank and "57200" on the front, "M.A.G 27" on the left side, "M A R. TPD. SQD. III" on the right side. This hat is very cool and likely saw quite a bit of action as I know the Marine Aircraft Group fought at Midway.