Fons & Porter 3-to-12-Inch Easy Diagonal Sets Ruler
With this ruler, cutting side setting triangles and corner setting triangles for diagonally set quilts is a snap. All the math is done for you. Simply cut a fabric strip, then cut the side and corner setting triangles from the strip. The Easy Diagonal Sets Ruler is designed to cut setting triangles for blocks that finish 3 to 12 inches square.