N/A Compressor GX PUMP E-CS4- why are there 2 pointers on the fill pressure manometer?

Hi guys

sorry for another dumb question from a newbie but i don't understand why the fill pressure manometer has 2 pointers..

i thought it would have just one pointer -for me to tell the pump at which maximum pressure it needs to stop pumping but what am i supposed to tell the compressor with the second pointing arm- the minimum pressure... what for?



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