This Over-the-Head Intercom Headset is our standard, pit-cart intercom headset. This headset allows for a connection to the intercom on one side (BLUE and RED buttons) and connection to a second, handheld radio on the other side (BLACK button). Pressing the handheld radio PTT (BLACK)-button, keys the handheld radio, while simultaneously muting your microphone going to the intercom. Pressing the intercom PTT (BLUE )- button keys the radio connected to the back of the intercom. This headset also comes standard with a latching (RED), microphone-mute button so that you can completely disable your microphone audio going to the intercom.