I believe the buckled cable is part of the electronics bricks set of sensors. I think these originally came from Seeedstudio: http://www.seeedstudio.com/depot/electronic-brick-fully-buckled-3-wire-cable-5-pcs-pack-p-485.html
If you live in the USA, the distributor robotshop sells them for faster delivery :http://www.robotshop.com/seeedstudio-electronic-brick-3-wire-cable.html
I'm sure there are other US distributors you can get these from, just search around.
If you don't have the bucked cable on the other side, you can always use wire cutters to cut the wires, and strip the ends for normal male cables.
You can use the normal 3 pin interface instead of using the buckled bricks, using 3 joined female/female cables, or female/male depending on your needs, possibly using hot-glue or solder to attach them for more stability.
Here is an introduction to the electronic bricks: http://www.rugcommunity.org/page/seeed-studio-electronic-brick