I would like to see some thermal imaging studies performed before I would count on this product do what the manufacture’s claims. This product cannot fully encapsulate you the way you can with the heatsheet (covering one’s head and trunk, effectively blocking the wind – convection loss). We have discussed the use of an inflatable air mattress in terms of heat retention, which they do not, although heat loss is through conduction (contact with the ground) more then from radiation or convection loss that the vest would theoretically block. It seems the claim to fame is that you are inflating the chambers with air warmed by the body via one’s breath and that might have an initial warming effect, but as soon as the heat is transferred from the trapped air to the outside air, this short term benefit would be quickly lost. Trapped air with that degree of volume will still allow for body heat to be transferred from the body to the outside air as the chambers cool off and start robbing the body of heat. Is it better then nothing? Sure.

Pete