A standard dose of a HELO Air vaporizer is 10 puffs, which contains about 1.3 mg of caffeine (depending on how deeply you inhale). That may sound like a small amount, but remember that it's absorbed more efficiently. Many of our users quickly find that they don't need more than 3-5 puffs to feel pumped up and energized. With 400 puffs in each device, that means it will typically last you at least a couple of weeks. Lighter users may only need to replace theirs once a month or less. The HELO Plus holds twice as much and lasts twice as long (but it doesn't cost twice as much).