This is a perfect tool for many quilting projects. Perfect for cutting over-sized squares, checking finished sizes, checking seam alignment, and cutting large 45' triangles. Can also be used as a portable light table!This is the perfect for squaring up your 12" blocks, and is one of my favorite tools. It also works for smaller blocks and over-sized triangles, too. The Ruler is 12 1/2" square -- the blue lines make it easy to see on nearly every fabric