Square up 2 sizes of quilt blocks with 1 ruler using just a rotary cutter, no need to mark or trace. 1/4 seam allowances on all sides-interior and exterior. Teardrops allow for complete corner cut of interior square. 3 color grid markings for easy-to-read dimensions, black = 1 and 1/2 teal = 1/4 and magenta = 1/8. 45 degree markings to visually square block designs.