The CU-380 automatic antenna tuner was designed to match the Collins KWM-380 to a single wire antenna of at least 16 feet long. The unit has a coax input connector and a well insulated antenna output connector. I removed the top cover for the lower right picture. It is controlled by what appears to be a custom microprocessor. The terminal strip on the top of the control board connects to a special cable that links the CU-380 to the DB-25 connector on the back of the KWM-380. The cable exit can be seen in the bottom picture. A interesting story -- I did not receive the cable when I purchased the CU-380 so I emailed Collins Rockwell sales. After much help it was determined that this component was no longer in production. They were great! I told them I understood and thought "I guess I will make one". About a week later I received a box from Collins Rockwell with a used cable (of course they could not sell me used merchandise). What a class act!