AceBeam 10440 Li-Ion Battery
One of the smaller Li-ion batteries around, this is still a powerful, rechargeable unit that will keep your flashlights going for years. While we recommend you insert these 10440s in your separate charger of choice instead of inside a flashlight, using the tools at your disposal is not bad.
You'll have good charging speed inserting these batteries into a Nitecore F1 charger while on the go. While it only takes one at a time, the small size makes for shorter time in the F1.
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AceBeam UC15 - 1000 lumens - CREE XP-L, XP-E2 & Nichia 276A LEDs - AAA x2 or 10440 x2