Rigid, simple, cold-war tested and reliable.  This unit, while slowly being phased out, is still extremely popular amongst the professionals due to its simple construction and relatively low repair costs. 

Specifications:
Range: 0 to 10 R/hr in two ranges:
- High: 0.1 - 10 R/hr
- Low: 0 - 100 mR
Accuracy: +/- 20% over the entire range
Batteries: two 9V cells
Operating Conditions: -18°C to +52°C (by ensuring adequate battery voltage, operation down to -40°C can be achieved)