What does X over K mean on a radar detector?

Police radar transmits radio waves on a specific frequency, and the three frequency bands currently in use (in North America) are X-band, K-band, and Ka-band .

X-band is widely used because of the ability to utilize smaller antennas that fit on most boats and to provide better target resolution. S-band radars are often used for specialized applications, such as seeing through heavy weather or precipitation and for long-range bird detection. S-band antennas are larger .

X-band alerts (“Beep”) are often found at long distances . K and Ka bands are usually detected at closer range, and alerts on those frequencies are much more likely to be radar. So Valentine One makes a different sound (“Brap”) to warn you of these more urgent threats (bogeys).