Mobile measuring device for quick and precise measurement of the effectiveness of purvection on an object. With the PURVECT AIR Ion Counter Type Quali, the rapid and precise effectiveness of Purvection can be confirmed when the Purvectors are started up. With the attachable sensor, the Purvection in the Supply Air Ducts can be easily checked. The PURVECT AIR ion counter type Quali has 4 LEDs, which make the quality immediately visible. Its bigger brother PURVECT AIR ion counter type Quanti can also show the quantity of Purvection via a display.