The Whirlwind PB12 is a passive Pressbox microphone output expander, housed in a rugged steel case, for that company's PRESSPOWER2 and PRESSMITE active press box line outputs or any other live press conference or forum application where a line level feed is available. The PB12 distributes one line level input to multiple mic level outputs. Each output is transformer isolated, providing superior inter-channel isolation and ground lifting, to help eliminate noise problems and Whirlwind's own TRSP-2 transformers are used throughout.