There are two designs of weight training machines available for this exercise. The seated lever fly machine, and the Pec Dec. The seated lever fly involves grasping two handles at shoulder height, and pushing them together while keeping the elbows at a constant angle.1 When using the Pec Dec machine the hands grip two handles at head height, while the forearms push against two pads at chest height.2 The anterior deltoids are used as synergists in both variations. The biceps brachii act as a synergist in the seated lever exercise, but not on the Pec Dec due to the raised arm position.
In some machines, the seated lever can be adjusted to perform a rear delt fly exercise.
Lever Seated Fly at exrx.com http://www.exrx.net/WeightExercises/PectoralSternal/LVSeatedFly.html ↩
Pec Dec fly at exrx.com http://www.exrx.net/WeightExercises/PectoralSternal/LVPecDeckFly.html ↩