Descriptions:

The GT-521 Handheld Particle Counter is a full-featured, battery-operated, portable laser particle counter that provides the functionality of a bench unit with the convenience of a handheld! It can datalog particle counts continuously or send them to a network.
Two programmable particle channels with a range of 0.3 - 5.0 microns each show differential or cumulative particle counts in real time, with selectable count units.

Specifications: 

Measurement Method:	Scattered laser light
Particle Size Range:	Two channels - from 0.3 to 5.0 μm (selectable in 0.1 μm increments)
Concentration Range:	0 – 3,000,000 particles per cubic foot (105,900 particle/L)
Accuracy:	± 10% to calibration aerosol
Sensitivity:	0.3 μm
Flow Rate:	0.1 cfm (2.83 lpm)
Sample Time:	Adjustable: 6 to 999 seconds
Hold Time:	Adjustable: 1 to 999 seconds
Electrical
Light Source	Laser diode, 35 mW, 780 nm
Power	6V Ni-MH self-contained battery pack—provides 8 hours of typical intermittent operation, up to 5 hours continuous use
AC Adapter/ Charger	AC to DC module, 100 – 240 VAC to 9 VDC @ 350 mA typical
Power
Communications	RS-232 or RS-485 Half Duplex
Certifications	Meets or exceeds CE, ISO, ASTM, and JIS international certifi cations
Interface
Display	16-character × 4-line LCD
Keyboard	7-key membrane type
Physical
Size	Height = 6.25” (15.9 cm) Width = 4.0” (10.2 cm)
Thickness	2.1” (5.4 cm)
Weight	1.94 lb - 31 oz (0.88 kg)
Environmental
Operating Temperature	0º C to +50º C
Storage Temperature	-20º C to +60º C