Use the vertical, horizontal and diagonal lines to square up any rectangle
or any flying geese unit up to 4 1/2" x 8 1/2". 
Center the design and mark the design through the holes with a water or air soluble marker. 
Connect the dots. 
This is the finished size of the rectangle. 
Then add the 1/4" seam allowance which is marked on all sides of the ruler.

To fussy cut, center a design in a rectangle from 1" x 3" to 4 1/2" x 8 1/2`
Rectangles are marked at every 1/2".
The drilled holes at at the corners let you mark the finished size of the rectangle. 
Then add the seam allowance to fussy cut pieces using the 1/4" seam allowance
marked on all sides of the ruler.
The embedded grippers hold the fabric while cutting.

Also, turn the ruler over and use the holes to draw circles
with various diameters in 1/2" increments.
(You need to turn it over so it will flow smoothly
and not be held by the embedded grippers)
Comes with directions.

4 1/2" x 8 1/2"