This exercise makes for a great finisher after a shoulder workout. It'll hit all three heads of the delts. The key here is continuous tension, one of the key mechanisms for muscle growth.
You won't need much weight for this one. We're going for time under tension and burn.
Perform a lateral raise, followed by bringing the dumbbells together in front, then a front raise from that mid-body position. Now reverse the movements. That's one rep. If you do it right, you'll never lose tension on the muscles.