You can link up to 2 cables together (at least that's my success, I have never been able to get 3). The piece of hardware is called a "barrel connector." You can find these at Radio Shack, Best Buy, Home Depot, Lowe's, etc. They're about 1 1/2 inches long, squad and each end plugs into it. They'll cost 1-2 dollars for a set of 2.