The CD V-700, as a true Geiger counter, is capable of measuring ambient background levels of gamma radiation and detecting the presence of beta radiation in the environment, and thus can be used to detect such common low-level radioactive artifacts as uranium-doped marbles, Fiestaware plates and radium watch faces. This differentiates them from other civil defense radiation meters such as the CD V-715, CD V-717 and CD-V-720, which are ion chamber meters that can measure gamma radiation levels far above (up to 500R/h) what the CD V-700 can (up to 50mR/h). Conversely, the ion chamber units are so insensitive to low-levels of gamma radiation that no legally exempt radiation source can make them register at all.  
The CD V-700s were usually packaged in various combinations with the high-level ion chamber units as listed above in kits designated CD V-777. In their original Cold War application, the sensitive CD V-700s would be saturated and thus rendered useless by the high radiation levels expected after an exchange of nuclear weapons. In that setting, it would be the ion chamber units that received most of the use. The CD V-700s main purpose was as a peacetime training instrument and for use in checking food and shelter entrances for low levels of fallout contamination. Later, as the Cold War mission wound down, many CD V-700s were re-purposed as instruments for first responders to use at the scene of a radiological event or other incident.  
As the CD V-700s produced for the US government are now over 50 years old, they are being slowly replaced by more modern instrumentation in US federal and state government stockpiles and these older units are being sold off as government surplus. This makes them inexpensive and very common in the US for use by uranium prospectors, physics teachers, radiation hobbyists and others interested in detecting and measuring ionizing radiation.
CD V-700s are relatively simple devices, with a circuit board that employs a few dozen electronics components, at most. Thus, the CD V-700 is a common target for various upgrades and modifications that enable added functionality. Most of the parts used are common off-the-shelf electronics parts, but some models employ transformers and other parts that were custom-made just for that particular make and model of CD V-700 and these can be difficult to locate and replace in the event of a failure. Considering their age, the CD V-700 is a fairly reliable device and are usually fairly easy to keep operational over time.
The battery limits the range of temperature at which the device works from between −10 degrees C and 40 degrees C.