A pretty interesting new product out. Curious as to the effectiveness of it. Claims to prevent most swelling after an impact to your helmet, by cooling your brain. Containing the same contents as an instant cold pack, there is a layer of ammonium nitrate and water that mix to create an endothermic reaction.
"The chemical reaction will maintain a 37-degree [Celsius] brain temperature, which is said to stave off oxygen loss to the brain.
According to Thermahelm, its technology will add roughly $250 to the cost of a helmet, and the company is currently working on a retrofit kit that will allow riders to install the system in their own helmets."
http://www.autoblog.com/2009/12/09/v...swell-err-not/
http://www.thermahelm.com/