This was plugged in to, and dangling out of an Apple IIe I got recently, the computer works without it, and as you can see it has a 4 pin plug on the wires and two RCA female plugs on the box.
There are only a few things silk screened on the PCB: "Biwave Out" & "1003-0030 Rev. O". I'm not fluent in Apple IIe components, but this looked interesting, but didn't do anything to the operation of the computer over all. It plugs in near the composite out in the right back corner of the mainboard.picture here
Yarrgh! The link showed the entire directory, my apologies link fixed here