Optimus's Fuel Bottles are for use with multi-fuel stoves such as the Optimus Nova Plus stove. These bottles are designed to hold fuel and to be pressurised.
Optimus says:
Optimus fuel bottles are suitable for transporting and pressurizing all kinds of liquid fuel. Thanks to a unique hardening process, these bottles are strong and durable, yet surprisingly light weight. With child-safe-cap. Available in three sizes: S 0.4 L, M 0.6 L and L 1.0 L.
For use with the Optimus Nova Plus mutlifuel stove.