Thanks I've decided not to use this bottle. I've just received from you a welding gas adapter and can get a 1kg refillable bottle so going down that route refills are easy to get at local auto factors down the road.Hi @simon Coram Yes it's a CGA 320 Paintball valve. It's harder than you might think to get Paintball cylinders refilled these days; a lot of places are switching from using CO2 to compressed air, and some only let you refill if you're then playing at their centre. I recommend phoning up, rather than wasting your time driving to places.