The one I had was made by a company called "Johnson" (I think) and it had a metal spring soldered onto the back. The one I saw exposed on TV had some kind of rubber band on the back. I can't speak for that one.
I can say that the Johnson Cig Thru Quarter that I had was VERY NICE! The cigarette was seen to go into the quarter from the tail-side and the "work" was UNDETECTABLE even if you felt the quarter with your fnger. The other side can not be shown at anytime.
If you know a good coin switch or two, this is a MIND BLOWING illusion (if they don't already know the secret). Unless someone actually knows how a quarter can be rigged to do that, it looks just like magic. To "borrow" someone else's quarter and do it leaves them with no logical conclusion.
To pull this illusion off well, I think you MUST be able to switch the special coin for a normal one UNSEEN and UNSUSPECTED and most of the practicing I did on it was basically the handling of the switch. Once the switch is invisible, the rest is pretty easy.
David Copperfield performed it on TV on his "Walking Through the Wall of China" special.
I performed it almost daily for years and most people really freaked out. My Dad used to take me to the bars with him and I got a reputation for it and numerous requests. It has got to be one of the strongest close-up illusions that could be done until... Fox Television's horrible destruction of it.