MARTI MICHELL-My Favorite Squaring Up Ruler. Use this ruler to make perfect seams! This package contains one 6-1/2x6-1/2 inch square ruler with quarter inch seam allowances. Made in USA. WARNING: This product can contains chemicals including Poly(methyl methacrylate), which is known to the State of California to cause cancer. For more information go to www.P65Warnings.ca.gov.