Quarter sawn lumber has been cut through the heart of a log and thus the annular rings are perpendicular or 90º to the face of the board. The result is an extremely stable board and can produce spectacular grain patterns (i.e. Ribbon Stripe Sapele or Leopardwood). This is usually more expensive lumber since only a very few boards can be sawn out of a log this way. The grading system will accept 90º-60º ring angle in the board.