I used a 6.5" one to square up 3" blocks. Easy as pie. I might get one larger one and I think between the two, I'd be set for any size HST. I was also able to use my Eleanor Burns 3 x 6 flying geese ruler to trim my 2.5 x 5 flying geese. I just had to use the one side to get the "point side" just right and then used a ruler for the rest. Having that angle printed on it really helped me to trim the point side just right.