This beanie feels nice and provides reasonable warmth. However, I think it runs small. My head measures about 22.5 inches, yet the L/XL size fits me perfect. I am sure the medium, which is my regular size, would have been too small.

UPDATE: My initial review was for the BLUE hat. Now, I also have the black one in the same size L/XL. The BLACK turned out to be slightly smaller, but still fits my medium-sized head.