3 article size sensitivities are available from 0.1, 0.3, and 0.5 microns. The 237′s count airborne particles in up to six size channels with alarms for each size. Features are, simple front panel operation, stores up to 500 count samples at up to 250 location and includes RS232C and RS485 interface. It is AC or battery operated. Includes programmable count times, internal printer, four modes, sensor alarm and a low battery indicator. Options include Temperature and Humidity sensor.