Demountable camper group

Clever isn't it
would be good to get something a bit more scientific than a big heavy extinguisher

It is a bit of a gimmick. Yes, it does look to do a fine job of a fire that's fully vented to the outside air. However, if it's your home, it'll most likely be a sealed or partially sealed compartment fire. In this circumstance, the bomb will go off and temporarily extinguish the fire, but the heat remaining in the compartment will not have anywhere to go, so everything will heat up agin very quickly, the extinguishing media will break down and the fire will re-ignite. At the end of the day, as long as leccy's not involved, you can't beat good old H20.

I don't think I would want to be in a room with one of those going off!

Anything like the powder extinguishers anyway,
Those things make a hell of a mess inside a closed space