Quilter's Rule 12-1/2-Inch-by-12-1/2-Inch Quilter's Lap Board
Quilter's Lap Board is a square grid molded ruler for measuring and cutting 1/4 inch up to 12.5 inch squares.  Handy for a true block to size.  The lines and numbers are molded right into the plastic for a fabric gripping action.  Lap board measures:  12.5 by 12.5 inches.