Electronic – the largest electrical connector in the world?

They are mini-banana plugs and jacks. Pomona is one company that makes them:

http://www.pomonaelectronics.com/pdf/d2945_100.pdf

http://www.pomonaelectronics.com/pdf/d2143_1_01.pdf

Digi-Key stocks them.

It's more commonly known as an M12 connector. They're industrial connectors used for remote sensors or ethernet. There are a bunch of people that make them. There are smaller versions too, the M8 series.

Several companies make them.

http://www.te.com/catalog/minf/en/856

http://www.molex.com/molex/products/group?key=brad_m12_product_families&channel=products

For some product page links. Binder USA also makes them, and a number of other industrial manufacturers.

You can also find them from distributors like Digikey and Mouser. (Just search M12)

As long as they're the same number of poles and have the same keying, they should fit. I'd order a sample from Molex or TE and double check.

I would stress relieve the connector if you're doing a PCB mount, the mating force for these is pretty high. All the PCB connectors I've seen are panel mount.