Bren and others
I was at Electronic Design Show in Coventry UK today and came across some nice IP68 circular size 00 USB connectors by a company called ODU who are based in Germany. The connectors are similar to Lemo size 0 but cheaper
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The come in "break away" or locking types. for the free plugs, and the sockets can be PCB mount or panel mount with a flex PCB cable to a connector on the PCB. Pricing isn't bad either (awaiting info). The also do size 00 power connectors rated to 3A if you want to bring in 12V as as well as the USB five volts.
They do prebuilt cables from their connector to a standard USB (2.0 or 3.0 depennding) in 0.2mtr or 2mtr lenghts.
HTH
Dave