Sit on a bench with feet flat and hold a dumbbell in each hand. Hinge forward at the hips with a flat back so your torso is angled toward the floor. Let your arms hang down with palms facing in or slightly back. Keeping your core braced, pull the dumbbells up and outward by driving your elbows back and slightly out to the sides, focusing on squeezing your rear delts at the top. Slowly lower the weights back to the starting position under control and repeat.
Log your dumbbell seated bent over rear delt row sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.