The key to having an efficient golf swing is understanding where your arms are from set up to downswing. The distance between your elbows should stay about the same throughout your swing. Many swing faults happen as a result of your elbows getting further apart.
Eric Cogorno explains how to keep equal distance between your elbows with the Smart Ball. The goal is to keep your hands in front of your chest while squeezing the Smart Ball between your forearms. If the Smart Ball drops at any point of your swing, that’s when you know your elbows separated.