SOL (Survive Outdoors Longer) ultralight reflective plasticised foil bivi bag. It reflects 90% of your body heat. The polyethylene material is quieter and more durable than traditional reflective bags and blankets.
Stuff sack included.
It comes vacuum packed and will take up about the same space in your pack as a medium sized apple - so there is really no excuse not to carry one!
Not breathable.