Tricep kick backs work all three heads of the tricep. Aaron Marino of alpha m. says to not go real heavy and to go nice and slow.
He demonstrates with the dumbbell and bench. Elbow is up about 90 degrees. Make sure to pause at the kick back. If you want to make it more difficult, lift your knuckles to the ceiling. You can also do this exercise with the cable. Lower the cable to your waist, brace yourself on the pole, and press back. You have the negative and positive resistance due to the pulley system.
