[MrForbes]

You do have to pay attention when setting up the connectors, to make sure they got them assembled in a way that keeps you from mixing them up. But you can also assemble them in different ways so not only are they polarity protected, but so that you cannot connect the wrong pair of connectors together.

We use them for the power system for our underwater robot, 48v at about 10A maximum. We use solar charging, and it makes a nice setup having these connectors keyed the right way, so things are always connected properly.

They are sold at a Tucson electronics store that I know of, so if you live in a decent size town you might be able to buy them locally.