I do not know at all the principle and I was rather subdued. For me it was a very clever find. Yesterday I learned that it was the principle of some lighters. But as I do not smoke, I do not know ;-) Finally, the system is simple but ingenious! Two small drawbacks: the capacity (5 ml, that's right, no?) And grip (grip is not so easy because of the aerodynamic shape that slips through your fingers There.!
