Shaft-Flex is determined by club head speed, hand strength, and flexibility. All three are comprised of elements that should be considered in a desired shaft-flex for each golfer. Shaft flex directly affects the club speed, squaring of the clubface at impact, trajectory and distance of ball flight. The shafts between clubs should be continuing in gradients of flexes (frequency matched) to assure successful fitting. Inconsistencies here could result in major accuracy problems for the golfer.