FAQ · Power
18650 vs 21700 — which should I buy?
Buy the cell your light takes; they are not interchangeable. If you are choosing a light, a 21700 holds roughly 30–50% more capacity for meaningfully longer runtime and higher sustained output, at the cost of a slightly fatter body. An 18650 light carries a touch slimmer. For most people the extra runtime of a 21700 is worth the girth.
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