This is the USB interface Module for the Overkill Solar BMS (among others)
This module is a USB to TTL UART adapter.
It will make a new COM port available on your PC,
which can be used with the provided software, or custom applications to monitor and adjust the parameters of the BMS.
FYI for experimenters: The BMS communicates with a 5v TTL UART at 9600 baud. It is directly compatible with Arduinos, etc.
The protocol is similar to MODBUS. requests and responses are in HEX. Protocol datasheet is available.