The flight direction of the ball is the result of the player's swing of the club at impact with the ball. To achieve the straighter flight with the greatest force of impact is the pursuit of all golfers. It is generally accepted that a player should not shift his body away from the target during his backswing; he should remain on balance during his backswing. It is also generally accepted that a player should shift his body toward the target during the start of his downswing. The player doing these two things has the best chance of the ball having a straight flight and long distance for the club used and the force of the swing.
Players do not generally achieve these two things because they can't perceive when they improperly shift their body away from the target on their backswing and they can't perceive that they do not properly shift their body toward the target at their downswing.
Various devices have been developed to help the player achieve a better swing, but most, if not all, have fallen into disuse because they do not give the player an immediate direct "feel" and signal indication of whether he has properly and/or improperly controlled his body relative to the increments of his swing. The "feel" is the more important. The "feel" of making a proper swing is almost impossible to perceive and recognise. It is believed that none of the prior art apparatus give the player not only the "feel" of making a proper swing but also fail to give him the "feel" of making an improper swing. Until a player gets this "feel" he cannot controllably and predictably execute a proper swing.