I believe the emergency bivy they sell (the smaller package of the two bivy bags on their site) is made of the heatsheet material.

What is surprising is that, the way their advertising reads anyways, the smaller packaged bivy seems to be higher rated for keeping you warm. That seems counter-intuitive to me. Even if it isn't as I perceive it to be, I still prefer the smaller packaged bag for packing convenience. I bought some last Xmas as stocking stuffers for the girls, and as more gear for me.

Those yellow whistles look a lot like the Fox Micro 40 ones I own.

I have yet to try out the heatsheet material in cold climate. I would like to see how effective the thinner bag really is.