Opera Cake is an antenna switching add-on board for HackRF One that is configured with command-line software either manually, or for automated port switching based on frequency or time. It has two primary ports, each connected to any of eight secondary ports, and is optimized for use as a pair of 1×4 switches or as a single 1×8 switch. Its recommended frequency range is 1 MHz to 4 GHz.

Documentation: github and read the docs