We know those big exercise machines at the gym can be intimidating, but the next time you hit the gym you should consider making friends with one of them because they offer a resistance (often adjustable) that you can't get with workout tapes at home.
If you want to do an excellent arm toning exercise at the gym, check out this video to learn how to do a cable rope pull down/tear apart to tone your triceps.
The rope pull down / tear apart exercise is a great triceps exercise. Work very hard on linking up your "mind muscle" connection.
"Squeeze water out of a sponge" in the tricep area during the contraction; especially during the top of the positive or concentric phase of the movement.