I have the North Carolina QuickPass EZPass mounted to my bike. The QuickPass is good for all EZPass states as well as the Georgia PeachPass and the 2 Florida systems. I also carry a Kansas K-Tag that takes care of Kansas, Oklahoma and Texas.
The NC QuickPass EZPass is similar to the exterior bumper mounted transponders used for certain cars. Two years ago when I ordered my pass, it was the only one available for motorcycles. The white interior mounted pass would not work for my m/c but works just fine for my truck. I just have the bumper mounted transponder zip-tied to my farkle bar and it works everytime.