Icom CY6000 DUP KIT UHF Duplexer

This duplexer is UHF 457-462 MHz,  (5 MHz minimum separation).

Duplexers allow bi-directional (transmit TX and receive RX) communication over a single path (i.e. antenna) at the same time.  The duplexer isolates the receiver from the transmitter while permitting them to share a common antenna.  In other words, the duplexer prevents the receiver and transmitter from "hearing" each other.