Specifications:
Detector:
Monitor 4: Halogen-quenched uncompensated GM tube with thin mica window 1.5-2.0 mg/cm2 thick.
Monitor 4EC: Halogen-quenched GM tube, energy compensated sidewall 2mm tin filter. Thin mica window 1.5-2.0 mg/cm2 thick.

Monitor 4 Energy Sensitivity:

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.
Detects beta at 150 keV with 75% typical detection efficiency.
Detects gamma and x-rays down to 10 keV typical through the window, 40 keV minimum through the sidewall of the detector.
Normal background is approximately 10-20 CPM.
Gamma Sensitivity: 1000 CPM/mR/hr

Monitor 4EC Energy Sensitivity Same as Monitor 4 except:

The energy response for gamma and x-rays through the detector sidewall is flat within +61% or -26% over the range of 40 keV to 100 keV, and within +35% or -17% over the range of 100 keV to 1.3 MeV (referenced to Cs-137).

Operating Range:
0-.5, 0-5, 0-50 mR/hr and 0-500, 0-5,000, 0-50,000 CPM
or 0-500 µSv/hr and 0-50 mR/hr.

Common Specifications:
Accuracy:
±10% of full scale (referenced to Cs-137)
Audio:
Internally mounted beeper (can be switched off for silent operation).

Anti-Saturation:
Meter will hold at full scale in fields as high as 100 times the maximum reading.
Power Requirements:
One 9-volt alkaline battery. Battery life is up to 2,000 hours at normal background radiation levels.
Temperature Range:
-20° C to 55° C (-4° F to 131° F).
Size:
145 x 72 x 38 mm (5.7 x 2.8 x 1.5 in.)
Weight:
M4: 178 grams (6.3 oz.) without battery
4EC: 198.1 grams (7 oz.) without battery
Range Switch:
X1, X10, X100, Battery Check.
Includes:
1 year limited warranty, carrying case, and CE mark.
Options:
Modification to run Observer Software. Stainless steel belt clip
(attached to instrument).