radar guns

/R EY1 D AA0 R G AH0 N Z/
noun
  1. 1

    A hand-held (or mounted) device that emits a radar beam and uses the Doppler effect to measure the velocity of moving objects (especially traffic)

Source: https://en.wiktionary.org/wiki/radar%20gun, https://en.wiktionary.org/wiki/radar%20guns