I love ball drivers. And the best I have seen are from RTL Fasteners. They have a detent on the ball that keeps the screw on the driver no matter what angle. These are much like the detents used in ratchets that keep the sockets or extensions on the ratchet at any angle. You can put the screw/bolt on the driver and then start it at any angle, vertical, horizontal, whatever, and the screw stays on the driver. You have to actually pull it out of the screw after the screw is tightened.