Fly exercise is usually done by dumbbells. The motion is almost the same, and you can do it on a normal, incline or decline bench.
Nevertheless, there is a fantastic version of this pec exercise, the one arm kettlebell bench fly. This activity needs a powerful upper body considering that you must control your entire body to keep the balance. It also works your abs, triceps and shoulders. It is also an excellent one for stretching, and I love doing it.