This pattern requires the purchase of either the Skinny Robin or Fat Robin 16-Point Mariner's Compass Book and Ruler Combo (or the former Skinny Robin 45˚ AND/OR Fat Robin 60˚ Mariner's Compass Books/Rulers. If you have the former Skinny Robin AND/OR Fat Robin Companion Booklets, you will be able to create even more mariner's compass blocks). Info from this pattern is contained in the corresponding Skinny Robin or Fat Robin 16-Point Mariner’s Compass Book.