Per the website: "PowerTrekk uses eco-friendly fuel cell technology which cleanly and efficiently converts hydrogen into electricity. The ability to simply insert a PowerPukk fuel pack and add water provides users instant and limitless power on the go."
This seems to not match up to my understanding of fuel cells, which use hydrogen and atmospheric oxygen to produce electricity and water. My guess is that the water is used to somehow activate the fuel which is stored as 'flexible stickers' not hydrogen gas.
This would be a nice thing if the fuel is cheap enough over time and it doesn't turn out to be vaporware.