Hubby is trying to kick his smoking habit. I gave him e-cigarettes last Christmas to help him out. These things do run out like the regular cigarettes so I also bought several electronic cigarette replacement cartridges as backup. One cartridge is only good for some number of puffs. It’s imperative that he should have some in reserve as these are hard to find. It seems to be working so far. Hopefully it would really end his smoking habit.