Pelz's theory on successful putting is the chances of making putts are optimized when the ball rolls at a speed that would stop 17 inches past the back edge of the cup (if it misses). His 'phoney hole putting speed' Trainer has a white line (with a 17 inch reminder) on one side, which can be placed to help you find the incoming line and break of your putts. Phony hole is slightly smaller than regulation at 4" instead of 4.25". The phony hole is designed to help you more accurately see your line and speed on putts of all lengths.