Effortlessly cut, mark and stitch 1/2-square or 1/4-square triangles without ever cutting a triangle or guessing at the size. This gauge makes it quick and easy. Slide the corner of your fabric square into the corner of the gauge, slide the slider to opposite corner and lock in place. Then reference the left side of the gauge for 1/2-square and the right side of it for 1/4-square triangles. Mark your stitching line down the center of the gauge. You can make 5 block sizes for both 1/2 and 1/4-squares: from 2-1/2" to 6-1/2".