These units are approved for aircraft below 175kts/15000 feet, but both manufacturers make similar units for higher speed/altitude.
Don't you just love the totally blatent cynicism of aviation marketing
It's the same damned product.
I would like to know what is the real meaning of an "aviation approved" lithium battery. It's a bit like a barbeque approved for use inside a petrol refinery.
Wigglyamp - should there be a problem with a transponder which is fixed to the (non-electric) aircraft's panel, and the battery being on a flying lead with a connector? That makes the battery portable, and portable stuff does not need approval (except for transmitting equipment where the CAA has the responsibility for approving e.g. Icom handheld transceivers).
It also means that if the battery starts smoking, you can unplug it and chuck it out of the window (if you have a window at all).