This exercise targets the forearm flexors and allows you to work each forearm individually, thus helping to develop balance and proportion between both forearms. 1. Sit and hold a dumbbell with an underhand grip. 2. Rest your forearm on the bench between your thighs with your wrist just beyond the edge of the bench. 3. Allow the dumbbell to roll down the palm towards the fingers. Curl the dumbbell back up and flex your wrist. 4. Once you perform the desired number of reps for one arm, switch and repeat with the other arm.