What causes a slice? Conventional thinking over the years has been that an “outside/in” swing with an “open” face will cause a slice. New technology (TrackMan) has provided us with the ability to MEASURE exactly what the club is doing as it approaches and exit’s the impact area. The TrackMan is able to provide accurate data within one tenth of a degree. New data indicates that for a pull-slice, the club path is indeed “outside/in”, but that the clubface is actually, CLOSED at impact! Thus, the ball flight starts left and curves back to the right with clockwise spin (slice). The face of the club at impact will account for 85 % of ball flight direction, path accounts for 15%. In the example above, the face can be closed excessively and that combination of outside/in, excessively closed face will cause the dreaded “pull-hook”. If the club path is too inside with an “open” face, the resulting ball flight will be a “push slice”. TrackMan measures the spin of the ball with an accuracy of +/- 15rpm.