The power flye is basically a cross between a flye and a dumbbell bench press. The elbows stay at roughly a 90 degree angle. This is normally done on a flat or inclined bench.
With this floor version, the triceps should touch the floor but not the dumbbells. This makes the chest do more work without compromising shoulder health. Pause briefly at the bottom of each rep.
This is one of the best flye variations you can do for pecs.