This is a replacement battery for the GPD XD / XD Plus, from the original manufacturer. NOTE: For the GPD XD (not the XD Plus!), you might need to solder the connector to the battery, as some of these have an older, bigger connector.
To replace the battery, you need to OPEN the device and CAREFULLY remove the old battery from the case (it's glued onto it).
No need to solder, as the battery is plugged into the mainboard, but removing it from the case is not that easy.
Keep in mind that we can take no warranty for any damage caused by an improper replacement.