which nitecore?

Nitecore?
I have 4 Nitecores already, and continue growing...
Just some of my lights collection.



If you are new to 18650 battery or any other Lithium-Ion batteries, just make sure you use reputable batteries.
Avoid those batteries that end with "fire" like Ultrafire, Trustfire, Tangsfire, etc except maybe SureFire and Windyfire.
Get a reliable charger too, and avoid those brands I mentioned above.

If in doubt, get the Nitecore brand's battery and charger, although they are a bit on expensive side

I tend to buy my flashlights from online stores like Banggood, Gearbest, Fasttech from HK or China.
But I don't buy at their retail prices as you can get very good discount if you join groupbuy or ask for discount codes over at CandlePowerForums (CPF) or BudgetLightForum (BLF).
For example, the big Nitecore TM16 in my photo has a retail price of US$199, but using discount code/group buy, the final price is about US$120 including shippng.
Just a guide that normally Nitecore flashlghts can be had with 40-45% discount from their RRP if you know where to buy them, but caveat is you forego local warranty and have to ship your lights back to China for repair works or warranty claims.

As for batteries, I tend to buy Keeppower for protected button-top as Olight or Nitecore batteries are a bit expensive.
If you need flat-top batteries (but normally Nitecore flashlights need button-top), you can just get the factory stock batteries from Panasonic/Sanyo, Samsung, LG or Sony.