This is a simple bracket to hold a Jaycar supplied NI-MH Battery charger together as one unit.
The Jaycar catalogue number is MB3561 the link to their website for this item is below.
Note this is an Australian based store so this exact item may not be available in your country.

https://www.jaycar.com.au/60-minute-fast-charger-with-usb-port/p/MB3561

This can be used to keep the charger and the adaptor together for storage, I intended to use it to have the entire thing plug into the wall while this works it is only just holding on via the power outlet however on the floor in a power board it works just fine.
This style means it can easily be separated and used that way as well.