The thin sidewall Geiger-Mueller (GM) tube enclosed within the brass probe body detects beta radiation and gamma radiation with the detecting probe's beta shield open, or gamma only when the shield is closed. The brass body of the probe has an energy-compensation effect on the readings taken from the probe, reducing the over-reporting of events from low-energy gamma radiation as can be encountered with non-compensated GM probes.
In the case of the common Victoreen 6A model, the tube employed in the probe is an EON 62l0, of metal construction and halogen-quenched. It is sensitive to both gamma and hard beta radiation. The tube is approximately 90 mm long, has a diameter of 8.5 mm and operates at a relatively high voltage of 900 volts. The choice of this tube is intended to strike a balance between sensitivity and ruggedness and detects gamma radiation at energy levels of between 20 and 1000 Kev. The analogue dial is calibrated in both milliroentgens per hour and Counts Per Minute (CPM). When new and in calibration, these units can be expected to deliver accuracy to within +/− 10%. There are 3 possible scales of reading: 
* x1   (0–0.5 mR/h or 0–300   C/m)
* x10  (0–5   mR/h or 0–3000  C/m)
* x100 (0–50  mR/h or 0–30000 C/m)
A drop-in replacement for the EON 6210 or the 6993 tube is the LND 720, manufactured by LND, Inc. of New York, USA. 
A small number of CD V-700s were modified by the addition of a much larger end-window probe to detect alpha radiation in addition to betas and gammas and which operated at considerably lower voltages, resulting to changes in the high voltage electronics. These units were redesignated as the CD V-700M and were issued on the basis of six units per state emergency management agency. Their primarily intended use was for detecting and cleaning up low-level radioactive contamination in state RADEF calibration laboratories, though they could be used to detect alpha radiation in the field, if needed.