I've bought both the 004, and 005 cables. it wasn't immediately quite clear which cable I needed to record to my Gopro, and I bought the audio IN cable, 004, and I couldn't work out why I wasn't able to record sound to my media mod, even though it had an audio cable- I realised I needed the 005 cable, and now I can record the sound simultaneously from both my Radio, my Bluetooth And when I press the PTT, my voice as its passed through the sidetone. I haven't yet used the VOX feature, though I expect it can record to my Gopro too.
The 004 Audio in allows you to play music, say from an MP4 Player into your helmet earphones, whilst muting the music when a comms from your radio has priority, or a Bluetooth input, like Gaggle, or a phone message is incoming.
The 005 Audio Out plugged into a suitable recording device passes everything you hear in your headphones to the recording device.