I always used a piano wire, .40 thousands wide
Clip on shell catchers like you see on Remington 1100's and Beretta autos won't always work on the Super-X as there was a production change of the thickness of the receivers, therefore the people that made the clip on shell catchers stopped making them as they wouldn't work on most receivers.
Nu line guns used to have the factory clip on deflector that I used for doubles.
Bolsa Gunsmithing did mine, and more recently I had them drill my wife's Beretta 391. You can buy the wire at Ace hardware and make your own wires, as I have done many times.
Bolsa is in Westminster, CA.
Tom Strunk