This is an enclosure for a MaAnt Inductance Tester, this model https://s.click.aliexpress.com/e/_c4tULaUL 

This handy tool allows you to quickly check the condition of inductors and coils on electronic circuits without removing them. When a component is working correctly, the tester gives a clear indication; if the component is faulty, the signal will be absent or abnormal. It’s ideal for fast diagnostics on PCBs, mobile devices, laptops, and other electronics.