I have the 17" mat and the next smaller one. I bought the 17" because the squares I am cutting are 12 1/2" inches. I like the extra room of the 17" one. But, be sure your cutting space has enough room to rotate the 17" one. I tend to stack my cut fabrics on the cutting table and have to sometimes move the stack when I'm using the 17" mat. I haven't experienced a problem with it not turning easily. I'm thinking I would not want it to rotate so easily that it moves when I'm cutting. Good luck with your purchase and look for coupons.