No idea, but that looks a bit like something used for camping/caravaning/marine stuff. Lemme check a bit…
ETA: Found a shitload of IP67/8 connectors that would work, but they all have a notch/lug keying rather than that flat side that’s throwing me. Still looking.
FETA: Wow, there’s a lot of different sorts.
http://www.digikey.com/en/resources/connectors/index has got a really good set of filters that you might be able to play with and find the right one.
