What’s the difference between Survival Bivy / Bothy Bags?

We all know that we should carry with us some kind of survival aid, either for ourselves or others we might find on the hills.

Even in reasonable conditions, a slight accident resulting in immobilisation, can lead fairly rapidly to hypothermic situations if events turn against you.

You are no doubt aware that a survival bag, space blanket or bothy bag might be the item you ‘should’ carry, but which one?

Or more importantly, have these products changed over the years with the development of new fabrics and expectations?

Does this mean that there are new products on the market offering the same performance with less penalty?

This video shot on a perfect ‘survival’ day. Snow capped hills, a breezing biting Easterly wind and as I was so cold, it was a one take wonder. Unheard of normally, but I was too cold to do it more than once.
Thankfully it focussed my mind and proved just what an asset these items could be in similar situations.