The Proformance Plus Pec Fly / Rear Delt (PPD-803) by TuffStuff allows users to train the antagonist muscles of the pecs and rear delts for development and injury prevention. While bench pressing is no doubt a great lift for building an enormous chest and serious pressing power, big benches often come with a price in the form of pec pulls. Pec flyes are an excellent way to train the pecs to prevent pulls, particularly if you do them with light enough weight to train through a full range of motion and get a good stretch to help counteract all the hard contracting required during heavy benching.
Likewise, the rear, or posterior, delts are often neglected by big benchers while the front, or anterior, delts are overworked. The resulting strength imbalance can lead to shoulder girdle instability and susceptibility to injury over time. Rear delt flyes or raises are a great way to bring up the rear delts, leading to improved posture, better muscular balance, and reduced injury risk.