The 16340 is a 3.6v 880 mAh battery. Lasts me about 4 to 5 hours.
The 18350 is a 3.7v 1200 mAh battery. Lasts me 24 hours unless I am into real heavy
vaping for awhile. Most generally I change the 18350 every morning for a fresh one. I don't even bother with the 16340's now. They
have turned into spares.