When purchasing a NORM meter to be used for surveying for NORM, it is beneficial to evaluate the activity concentration options of the check source to be used. Check sources demonstrate the accuracy of meter detector (probe), and validates that the equipment is operating correctly when within its calibration time frame. In the past, the more popular 1 µCi Cesium 137 check sources have been utilized, however 1 µCi check sources typically read in the 400-600 µR/hr range, while many surveys have a highest reading of less than 200 µR/hr. Recently production has increased on smaller activity concentration check sources of 0.25 µCi. These check sources typically read in the 100-200 µR/hr range, and pose to be more representative for the typical oil and gas NORM survey. NORM readings can easily exceed 1,000 µR/hr, however the majority of surveys render much lower readings.