Start: Grab the end of a moderately heavy dumbbell with both hands and sit at the end of a bench With your palms around the bar and pressing up on the inside of the upper weight plate, lift the weight over your head, and hold it there with your elbows close to your head.
Perform that same movement while holding a dumbbell I each hand with a neutral grip, taking special care to keep your elbows close to your head.