This is an isolation chest exercise. The primary muscles used in this exercise are the mid pectorals. Secondary muscles used are the upper and lower pectorals
To perform dumbbell flyes grab a dumbbell in both hands and lay flat down on a bench. Make sure your feet are firmly planted on the floor.
Hold the dumbbells above you at arm's length with your palms facing each other. Next lower the dumbbells slowly as far down as possible keeping your arms slightly bent at the elbows. Keep your chest thrust out throughout the movement and return arms to starting position repeating process.