The copying ring, with a diameter of 3/8", is perfect for working with cutters up to 7/32" in diameter. You can easily centre it using the fastening screw. Indispensable when working with templates. For gauging routing templates. the copying ring can be precisely centred with centring mandrel 492187. for OF 900, OF 1000, OF 1010, OF 1010 R, KF