a communication equipment typically used by reporters in the past to intercept the walkie talkie used by police to obtain information [colloquial]
Definitions (粵典–words.hk)
名詞
記者用嚟截聽警察無線電嘅器材；當時記者可以聽到警察嘅通信，就可以趕過去採訪，甚至快過警察到場，後來警察換咗有加密嘅通信系統，呢種機無得再用，咁嘅情況亦都隨之消失 a device for eavesdropping on police radio communications; literally "nine nine device"