The Wio Terminal Battery Chassis is an extension board for Wio-Terminal Dev Board as it provides an external power source for Wio Terminal to enhance its portability and compactness.
It has a 650mAH rechargeable lithium polymer battery, battery charging/discharging status LED, 4 Grove Analog/Digital Ports, 1 Grove I2C Port, and 1 Grove UART Port, as well as the ABS enclosure for aesthetic and protection. The board has a BQ27441-G1A fuel gauge for LiPo batteries. There is also the same Raspberry Pi 40-pin compatible GPIO at the back of the Wio Terminal Battery Chassis for more add-ons.
More information is available on the website of Seeed Studio.