This device is a specially-designed electronic 'differential scale' for a peculiar use in blood banks. It measures two weights independently and displays how much which side is lighter than the other side.
For plasma separation from whole blood, blood bags are loaded in high-speed centrifuges. It is an essential process in blood banks that, before being loaded into centrifuges, weight of the two loads (each blood bag + bucket) has to be matched to be same or very close, otherwise weight unbalance could damage the centrifuges.
