Tricep Dip

Sit on the bench, put your hands on the edge of the bench, and place your feet hip width apart.

Press your body weight off of the bench so that your arms are straight, then slowly lower your hips below the bench until your shoulders reach elbow height (you do not need to go that low, however), then press your arms straight slowly.

Bench or chair

Arms  Deltoids  Triceps 

Chest 

Triceps brachii, pectoralis minor, posterior deltoids

TIP: Lower and lift yourself slowly and in control.