Dumbbell Scaption

Trains the Lateral Deltoid, Anterior Deltoid and Supraspinatus.

How to do it

Stand holding a light dumbbell in each hand at your sides, palms facing forward or thumbs up.
Set your feet hip-width apart and stand tall with your stomach braced.
Raise both arms in the plane about thirty degrees forward of straight out to the sides — halfway between a lateral raise and a front raise. This plane matches the way the shoulder blade sits on the ribcage.
Lead with your thumbs pointing upward, keeping a soft bend in the elbows.
Raise to shoulder height, pause briefly, then lower under control.

Raising straight out to the sides, which makes it a lateral raise. The forward angle is the whole distinguishing feature — it is what puts the load along the supraspinatus rather than across it.
Turning the thumbs down into an empty-can position. That version is widely taught and increases the muscle's share of the work by rotating the arm into a position many people find uncomfortable at the top. Thumbs up trains the same muscle and asks less of the joint.
Going heavy. Scaption is one of the few common gym movements that loads the supraspinatus directly, and it only does so at a weight that muscle can move.
Going above shoulder height. Past horizontal the shoulder blade has to rotate and the traps take over.