The string blocks are 5" (4.5" finished). When assembled in a 9-patch block, it measures 13.5" (13" finished.)
I'm not sure if that is the exact size used in Sunday Morning Quilts by Amanda Jean of Crazy Mom Quilts blog, but it's the size of my Accuquilt die. I like to cut my phone book pages with the die. After I sew the strings to the foundation I put it back in the die (usually only 2 at a time) and use the die to trim them. It makes for a nice, square block!
I also found a short little mystery QA that should finish before the Bonnie Hunter mystery starts. You can learn more about the mini fun at Humble Quilts Blog. It's called Cascadia.
I'm linking up with Angela at ScrapHappy blog. for the Rainbow Scrap Challenge, 2014.