Battery 3.8V 250mAh LiPo for Motorola MOTO 360 2 gen Smartwatch.
Moto 360 (2nd Gen 42mm) Battery - iFixit
Original Back Battery Cover Housing For Moto Series 2 42mm 46mm Door Rear Case For Motorola Moto 360 2nd Gen Lid with Adhesive|Mobile Phone Housings & Frames| - AliExpress