Help with protected battery for roche f12

Hi everybody,
Hoping someone can help me, the last time I bought a torch was a maglite 15 years ago so I am pretty confused by all the new terminology.
I was searching the forum and the roche f12 seems to fit my needs but still unsure about what protected battery will fit.
Will be buying the roche from fast tech, does anybody know if these will fit or if not any other decent batteries they have that will fit.
Thanks for any help.

Panasonic NCR18650A 18650 3100mAh 3.7V Protected Rechargeable Li-ion Batteries (2-Pack)

http://www.fasttech.com/products/0/10001980/1315402-panasonic-ncr18650a-18650-3100mah-37v-protected-re

Depending which F12 you choose, I don’t think it warrants a protected battery,
The F12 has low voltage protection, and can get very hot if left on high (2800mA) , you will feel it soon enough, I’ve gifted may of these lights with unprotected.

Depending which F12 you choose, I normally pick the 2100mA light, this gives enough power with out getting too hot, and is plenty bright for most needs.

On this fasttech sku it says it accept protected and flat top 18650.
On this thread it says that not all diameter of 18650 will fit, so the problem is not the lenght but the diameter of your batteries.

Length of battery is the main issue. You can put lengthy protected batteries in it, however it’s squeezed so hard against the driver spring that either they or the light ends up getting damaged. Trustfire 3000mAH batteries:
http://www.fasttech.com/products/0/10000377/1461701-trustfire-tf18650-3-7v-2800mah-rechargeable-li

are short for protected cells, and seems to fit o.k although I haven’t used these extensively and they’re still a tad longer than unprotected cells. They’re not bad budget cells with a true capacity of around 2100-2200mAh.

Personally I’d go with the panasonic 3400mAh unprotected cells, these are the cells I primarily use as they have the best capacity:

http://www.fasttech.com/products/0/10001980/1141100-panasonic-ncr18650b-rechargeable-3400mah-3-7v

I’ve had no issue with diameter on these batteries, unless you’re purchasing heavily re-packaged brand batteries you shouldn’t have any issues.

Thanks everyone for the advice, as I have zero knowledge about these batteries.