It shouldn't come as a surprise that cold water racing requires cold water protection. It's for this very reason that Blueseventy created both the Skull Cap and the Thermal Skull Cap found here. Both are constructed from 3mm Yamamoto Neoprene the same neoprene found in its Reaction wetsuit, which provides all of the hydrodynamics, warmth, and comfort that's found in a wetsuit. So, what's the difference' Well, the Thermal Skull Cap has been given a Merino wool lining. That's right, we said Merino wool. If you're remotely skeptical, you needn't be. Merino is naturally water repellent, and even better, this wool actually gets warmer when it's wet. In terms of fit, Blueseventy incorporated a flexible central panel along the top of the head. And as a result, the Skull Cap is conforming to most head shapes and sizes. Securing this fit, the cap extends over the ears and down into an integrated chin strap. This piece is soft and malleable, providing exceptional fit without inducing abrasion. The Blueseventy Thermal Skull Cap is available in one color and in the sizes Small, Medium, and Large.