The DC1700 Battery Operated Air Quality Monitor is a true laser particle counter. It detects particles in 2 size ranges >0.5 microns diameter and >2.5 microns diameter. It can be operated continuously using the provided International Wall Adapter or it can be operated for 6 hours straight on the internal rechargeable battery. This unit is an accurate laser particle counter which has been used in numerous projects at leading research universities/institutions to monitor both indoor and outdoor particle pollution. The internal memory can store 7 days of minute by minute timestamped data which can be downloaded for analysis and graphing to a PC (USB converter cable and DylosLogger software are included free). This unit responds rapidly to changes in particle levels which permits quick testing of air purifiers, air filters, air ducts, etc. This unit is EMI shielded to prevent any interference with the sensitive amplifier even in harsh industrial electromagnetic environments.