This is a ZC25-4 analog insulation resistance tester, also known as a hand-cranked megger.
It operates at a rated voltage of 1000V with a measurement range from 0 to 1000 MΩ.
The device is used to test the insulation performance of electrical components like wires, cables, and motors. [1, 2]
Would you like help interpreting the user manual text shown in the image?