Use tool simplifies making Diamond Square units without the need for paper foundation piecing. This all-in-one tool gives you a window template to accurately cut a center square. Ruler includes a chart printed on the ruler for the recommended size to cut triangles sewn to the four sides of the center square and a trim down section on the ruler to align ruler to fabric unit. Great for trimming units down to precise measurements every time. Six unit size options from 1" to 6" in 1" increments. For right- or left-handed use.