I was looking at the Fenix TK35 and while looking at what type of batteries it can take, I saw the following: Fenix recommends the Fenix rechargeable L2S/L2/L2M 18650 3400mAh 3.6v/3.7v, but they have a Caution under the rechargeable 18650 3400mAh Li-Ion 3.6v/3.7v.
Apart from the potential “just buy our brand” why would there be a difference?
Thanks