Putting to the smaller cup, 3 in. diameter compared to a regulation cup of 4 1/4 in. diameter, dramatically helps focus the golfers aim and trains them to make a more accurate putting stroke. The Sure Putt Practice Green System. A complete system that is widely regarded as the finest putting aid for any level of golfer. Offered at a tremendous value, it includes: * A Hole Cutter designed to cut a 3 in. (7.6 cm) wide by 3.5 in. (8.9 cm) deep hole. * 3 putting cups, 3 in. (7.6 cm) x 3.5 in. (8.9 cm) * Cup puller. * A sign to explain how the system works.