What does this switch do on the UK-47M1 panel?



When the switch in the down position, the h1 gauge indicates zero.
When the switch is in the up position, then the h1 gauge indicates like in the picture.

Better yet, what are the UK-46M1 and UK 47-M1 for? confused
Can an explanation of the swtitches, controls, and indicators be provided?
I notice that the h1 and h2 gauges move when missile(s) is(are) fired. Once the missile has detonated, the gauges return back to zero.
I guess that it has something to do with the radio fusing or guidance.