Check the listing for details. Doughnut PRO - Golf hole reducer/putting aid. Condition: New. Listed at 15.20 USD. A true putting test. We've added to the 'Doughnut' range and created the devilishly difficult PRO version of our popular hole reducer. Simply place ‘The Doughnut PRO’ into a cut hole on the practice green so that it sits flush with the surface. This precision engineered tool is exactly the size of a regulation hole (4.25” in diameter). It fits snugly in the hole and will have no problem maintaining its position. Practice putting to the new smaller hole (56mm – a golf ball is approximately 42mm in diameter). Only the most accurate putts will drop, providing positive feedback on the number of putts that hit ‘dead’ centre. Remove the device and the regulation hole appears to be a much bigger and easier target. Regular practice will dramatically improve your putting accuracy. If you think this is too tough, try starting with our standard 'Doughnut' (62mm diameter hole) and then progress to the PRO version.