Ebrorob - it's butano the same as the red bottles. Supplied by Cepsa - they are a hell of a lot lighter than the red bottles.
John - I would keep hold of the silver ones if you can as they are a lot easier to handle - I managed to swap 2 of my red for silver ones in a garage free of charge - but now anyone else who has tried is charged around 20 euros for the bottle as well as swapping
Haze