Woven synthetic or felt have been the two primary materials used to construct indoor putting greens. Now BirdieBall has introduced a third surface. This surface is made from high modulus, aerated polymer, foam. Now the surface grass texture and the soft sub-base work together to make the most authentic putting green surface on the market. The BirdieBall Indoor Putting Green surface is so unique that it has been awarded a patent. US Patent 8,979,663 Watch this video to learn the BirdieBall Putting Green difference.