Model; VARTA CP1254 + CP1454 rechargeable lithium battery
Size: 12*5.4 mm/14*5.4mm
Voltage: 3.7v Note,the battery size of this headset is different for the left and right ears.Before purchasing, make sure you have enough hands-on skills to complete battery replacement! 

Compatible with : 

Sennheiser momentum true wireless 1

The original battery has two negative poles, and only one of them needs to be welded to connect.

Package include:1x CP1254 battery with wire

1x CP1454 battery with wire

Tools