Birdie Ball Indoor Putting Green The 14 x 4 Birdie Ball Indoor Putting Green is made from state-of-the-art, 1/2 thick, shock-absorbing RollTech foam material which provides true roll of the golf ball. This bi-directional green has grass-like grain which creates a 10-stimp into the grain toward the two-cup end and a faster 11-stimp with the grain toward the one-cup end. It comes with three cups and three extraction flags which function exactly like the ones on the practice greens at your local golf course.