That's a CZ6 connector, therefore a CZ6 searchcoil. They're a waterproof industrial connector, did well in in-house stress testing and in field testing. In production, after a few months of usage in the hands of customers, they started coming back. We had to switch back to the sturdy but non-waterproof Switchcraft Slimline connector, which also required some minor retooling. Thus was born the CZ6a.
I hate loop connectors. They scare the heck out of me, and that particular episode is an example of why. It wasn't the first time, either. Both Fisher and Teknetics a few years earlier had adopted an AMP plastic connector, seemed real good until they started coming back. Both companies had to scrap them and go back to the Switchcraft Slimline.
Over the years I've figured out some of the reasons why circular connectors that pass qualification and field testing fail in the hands of customers. I'm not quite as afraid of loop connectors as I used to be, because nowadays I can look at what the vendor thinks is a great connector and 98% of the time I can say no thanks without ever having to put it through any tests.
The most shocking one was a couple years ago, a waterproof circular connector from a well-known connector manufacturer, looked good enough to actually test a sample. When I tried to solder the wires, the plastic melted. The manufacturer themselves had never actually tested the connector, I was the first!