What is the smallest CO2 cylinder size?

[blur2x]

Is it possible to get refillable (0.5~1L) cylinder (slim and tall instead of short and fat)? (like http://www.dennerle.com/CO2_NEU/co2_neu_comfortline.htm)

[PohSan]

Saw it in one of the LFS in serangoon north. Just opposite Rainbow, with plants display outside the shop. Owner is a taiwanese lady.
The diameter is about the same as the mineral water bottle but longer. Colour is dull blue so you might need to replain it.

[blur2x]

Thanks PohSan. I'll check it out this weekend.