The surface needs to be flat, like a manicured baseball or softball field. For natural turf, Bermuda grass is widely used on athletic fields. Find a suitable area in the outfield or along the base lines where the turf is maintained short and flat. For clay infield use, we recommend clay which is raked first and is as flat as possible. The mat also works great on artificial turf as well as concrete driveways. The mat will not work with long grasses such as St. Augustine, or Bahia grass as the grass is too high and thick to allow the ball to maintain its speed. The key to effective practice sessions is to ensure the ball rolls on as flat a surface as possible because the sewn seams in both baseballs and softballs also influence the movement of the ball.