Lie Down Perpendicular on the Bench.
Center dumbbell on chest and cross-hands over pushing up on the outer dumbbell.
Slowly push back and lower the dumbbell over and behind your head.
When the dumbbell is parallel to the floor, slowly pull the dumbbell back up and over your head and pause once the dumbbell is centered back on your chest. Repeat this range of motion for all remaining reps.