Unipivot Ammeter Pointer Galvanometer, by Cambridge Instrument

A rectangular metal box painted black with a window showing the scale of an ammeter. There is a large black knob on the front with numbers around the exterior. To the proper right of the knob, there are two copper alloy screws, one with a red circle around the base, the other with a black circle around the base, and both with black plastic screw caps on top.