It fits the 20V Yardworks and Worx batteries, as well as the generic 20V LiOn batteries sold on Amazon, so you can mount them on the wall for storage.

Note:To get generic 20V batteries to work, you simply need to use a multi-tool to remove the small plastic guide that various manufacturers place in different locations to prevent “incorrect” batteries from fitting into the tool. As you can see, the OEM Yardworks green battery retains its intact guide, while the generic orange battery has that guide removed so it can fit into the OEM charger and tool.