It is used extensively by Police Forces around the world, mainly for screening but also for evidential testing, and is Type Approved by the Home Office, Great Britain, for UK Police use in the United Kingdom.
The operator switches the instrument on and, when instructed, attaches a new mouthpiece to the small sampling port. He or she then instructs the subject to blow through it until the sample is taken. A short time later their alcohol level is shown on the clear, easy-to-read display: this is illuminated, for use at night.
When the reading has been taken, the operator removes and discards the mouthpiece. After a short delay the instrument is ready to use again on the next subject, as required. The result of the last test can be recalled to the display, if required.