First time I’ve actually heard of these, although I think I’ve seen them for sale and not twigged what they are. I’ve got an on-the-go travel flask from Morrisons, in fact I had two, one I kept for cold, the other for hot, but I dropped one when it was full which dislodged the bottom cap and wrecked its insulation, and they don’t seem to do them any more, which is a real shame, they’re very efficient at keeping drinks hot or cold.
I bought something else, but it’s not so good at keeping a drink hot for a long period, so these Chilly Bottles, or their clones, look like a good alternative.