This is a set of 2 fiskars acrylic square rulers, one 12-1/2-inch and one 6-1/2-inch. for dedicated quilters, these are the essential rulers for squaring off finished quilting blocks and centering half square triangles from 611/2-inch to 12-1/2-inch square. made of durable 3mm thick clear acrylic, they feature highlighted 1/2-inch seam allowance measurement as a visual reminder to user which side they are measuring from. center 45-degree bias line is clearly marked with measurements to aid in trimming blocks. optional non-slip vinyl tabs can be added or removed multiple times without damaging squares.