The single-arm cable cross-over is an isolation movement that uses a cable stack to build bigger and stronger pectoral muscles. Working the chest one side at a time allows you to focus on balance between sides of your chest, and really feel the chest muscles contracting. It is common in upper body and chest-focused muscle-building workouts, often in combination with other presses or flyes to target the chest from different angles.
Unlike dumbbells, cables provide constant tension, including at peak contraction
Ability to quickly switch weights for dropsets
Stretches the chest mucles under load, which can lead to greater muscle gain