Stand with feet shoulder-width apart holding a dumbbell in each hand. Hinge forward at the hips with a flat back and let your arms hang down. Keeping a slight bend in your elbows, pull the dumbbells outward and up so your upper arms move perpendicular to your torso, focusing on squeezing your rear delts and upper back at the top. Slowly lower the weights back to the starting position under control and repeat.
Log your dumbbell rear delt row sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.