It's called an "XREP". They can be found below...

"XREP" By Taser International

And below is the weapon that fires them. A specially designed Mossberg 12 gauge shotgun.

X12 - By Taser International

I work as a security guard and I had a former boss say that Taser international was working on building a new Taser with wireless probes. I believe this is what he was talking about.