Early detectors needed only to listen for X band radar. When K band arrived, dual band models able to receive both frequencies (X and K) were required.
The introduction of Ka band photo radar (34.3 GHz) led to the development of triband models able to detect X, K, plus a small portion of Ka band.
A fourth category of radar receivers called wideband, with X, K and "wideband" Ka (34.2 - 35.2 GHz) detection capabilities reached the market following the introduction of Stalker radar.
And finally, in response to the BEE 36A a new generation of radar detectors were developed termed superwideband, which cover all radar guns operating on X, K or "superwideband" Ka (33.4- 36.0 GHz).