Test your putting skills with these six fun hole reduction inserts. Once you have mastered making putts in the standard putting hole (4 1/4"), test your skills by trying to make more difficult putts with these fun hole reducers. They will reduce the size of the hole, and provide interesting aiming points.  You can also create a double depth hole with the double depth cup provided, which aligns the top surface with the cup and hole deepening shim that comes standard with your putting green. Specifications 6 Hole Reduction Inserts. They can be used in both the standard 1/2" deep cup, and in the 1" deep cup in conjunction with the hole deepening shim that comes with your putting green. Half Moon (1/2" deep) Half Moon (1" deep) Donut Shape (1/2" deep) Donut Shape (1" deep) Crescent Moon (1/2" deep) Crescent Moon (1" deep) Double Depth Cup (1" deep)