A last resort emergency device to enable escape from multi-storey buildings via descent from the outside of the builidng, irrespective of available electrical power.
Link to article: eandt.theiet.org/.../evacuator.cfm
Device url: http://www.evacuator.com
It currently has the EN 341 safety certification for personal fall protection equipment.
The analogy used in the article is that of an airbag in a vehicle, it is not the sole means of protection, but aids in saving lives.