On the front and rear light there is a 2.5mm UNBRACO that can be unscrewed – you can then easily change the batteries.
The front light uses 2 pcs AA batteries
The rear light uses 2 pcs AAA batteries
Empty batteries must not be left in the bike lights. There is a risk that the batteries will leak and damage the electronics in DeLight. Always change the batteries when the lights no longer turn on or when the app informs you about low battery.