The 1.0m A40 Mobile Cable, otherwise known as the Media Controller Cable or Media Cable, includes a volume wheel, inline mic, a mute button and a call pickup/hangup button. This cable is perfect for those looking to use the A40 with a phone or music device on the go: adjust your music volume and control your phone calls all via the cable. The inline mic has 2 settings - A to enable the A40's microphone, while B enables the inline mic in the cable itself. Note: in order to control your device with the cable, the switch needs to be in the B position