Halogen-quenched GM tube, energy compensated sidewall 2mm thin filter. Thin mica window 1.5-2.0 mg/cm2 thick. Effective diameter of window is 9.1 mm (.36 in.).
0-.5, 0-5, 0-50 mR/hr 0-500, 0-5,000, 0-50,000 CPM or 0-5, 0-50, 0-500 μSv/hr (SI Scale Meter Option)
1000 CPM/mR/hr (Cs137). Detects alpha down to 2.5 MeV; typical detection efficiency at 3.6 MeV is greater than 80%. Detects beta at 50 keV with typical 35% detection efficiency and beta at 150 keV with typical 75% detection efficiency. Detects gamma and x-rays down to 10 keV typical through the window (non-compensated), 40 keV through the sidewall.
Typically ±15% of reading (Cs137)
Internally mounted beeper (can be turned off for silent operation).
X1, X10, X100, Battery Check.
Analog Meter holds full scale in fields as high as 100X maximum reading. CPM & mR/hr scale. Optional SI Scale Meter Available
Headphone, 3.5 mm jack with pulse out.
Carrying Case w/ Belt Clip
SI Meter Option, Observer Software
1 year limited warranty
Monitor 4 Kits
Build your own Monitor 4! Learn about how a Geiger counter works!
9-volt alkaline battery (included). Approx. 2,000 hrs. at normal background
-20° to 55°C (-4° to 131°F)
M4: 200 g (7.1 oz) M4EC: 224 g (7.9 oz)
3.5 mm jack with pulse out.
209 x 71 x 50 mm (8.2 x 2.8 x 1.9 in.)