Abstract: A pair of error amplification deflectors, releasably attached to the face of a golf club with hook and loop patches, are spaced to provide a central zone on the face of the club for directing a golf ball along a normal path upon squarely striking the ball, but are shaped for redirecting the path of the ball upon striking the ball to provide a signal indicative of an off-center putting stroke or golf swing. The hook and loop patches permit adjustment of the width of the center zone for different levels of practice difficulty, and provide further indication of an off-center stroke by absorbing energy to decelerate the speed of the redirected ball.