 
This 31/2" square ruler was designed by Marsha McCloskey to measure from the center. Make extremely accurate 4triangle squares by first cutting the triangles larger than they need to be, then stitching the triangles to make a square. Center the Precision Trimmer 3 on the sewn unit and trim the edges to the perfect size.
UPC 640895370835

I also use the Precision Trimmer 3 as a point trimmer. Here are 2 ways to use the ruler to trim the 3/8" points from triangles.

