Immersion Research Thermo Cap
Here's what other sites are saying:
You've heard of a brain freeze before, but this is ridiculous. Surfing your kayak in a frigid washing machine of a hole is a better idea when you're wearing the Immersion Research Thermo Cap. Made with the same . 5mm brushed neoprene as IR's Thermo Skin tops and pants, this helmet liner offers a low profile so as to not funk with the fit of your helmet. A Lycra edge maintains comfort and a water-resistant seal.