Which battery should I use for the MKR IoT carrier? (Oplá IoT Kit)

Hi,
I've just started programming with the Oplá IoT Kit and now, I want to power my MKR IoT Carrier with a Li-Ion 18650 battery by using the built in battery clip.
The problem is, I don't know, which battery to use here, there are some with 3450 mAh, 3350 mAh or 2600 mAh or many others.
I don't want to damage the board with a too high current or make it not working with a too low current.
Which battery should I choose?

Get something from a reputable source and brand. The mAh rating just determines how long it will last for a charge.

Thank you for your reply.
It helped me very much. :grinning: