Most portable gas stoves will use either:

Propane: This is a widely available and clean-burning fuel option. Propane canisters come in various sizes, offering different burning times.

Butane: Butane is another popular choice, particularly for colder weather conditions as it has a lower boiling point than propane. However, butane canisters may not perform as well in very cold temperatures.

Most travel kettles are designed for a specific voltage range. Using a travel kettle with the wrong voltage will damage it or even be a safety hazard.

Before you travel, check the voltage requirements of your kettle and the voltage of the countries you'll be visiting. This will help you determine if you need a dual-voltage kettle, a travel adapter, or a different hot water solution.

Here's a general idea of what to expect:

- Well-made vacuum flasks, can typically keep beverages hot for 4-8 hours and cold for 6-12 hours.

- Larger flasks tend to retain temperature better due to the increased volume of insulation.

The ignition method will depend on the model of the gas stove, here are the most common ignition types:

Piezo Ignition: This is the most common and user-friendly method. Simply press a designated button on the stove, and a spark ignites the gas.

Match Ignition: Some models might require manual ignition with a match. This can be slightly less convenient than piezo ignition, but it's still fairly straightforward.

Leak-proofness in flasks can vary depending on the design and quality. Geepas flasks offer a spectrum of leak-proofness across the range, you must consider both the specific model and the intended use.