I am looking for a practical 300 bar day cylinder around 1 litre that will give about 3 good fills. I have got a 3l cylinder but that's a bit big to leave in the car all the time. I see the 500cc kits on Best Fittings, but they are a bit too small IMO. The best I've found so far is this: 2L/ 300 bar cylinder with valve Anyone aware of anything aound 1litre at 300bar? .