Dumbbell over bench one arm wrist curl

Sit on a bench with your feet flat on the ground and hold a dumbbell in one hand, palm facing down. Rest your forearm on the bench with your wrist hanging off the edge. Slowly curl your wrist upwards, bringing the dumbbell towards your forearm. Pause for a moment at the top, then slowly lower the dumbbell back down to the starting position. Repeat for the desired number of repetitions, then switch to the other arm.