I bought one for 4-1/2" HSTs, and though I used it for the whole project, I will never use it again. I much prefer Eleanor Burns triangle square up rulers. There are three different sizes. I purchased the middle size because that's what I found at JoAnn's, but may get the largest size if I need to make anything bigger than 6-1/2" square. The reason I like this one so much is because you trim before you press them open, so you only have to trim two sides. Trimming goes much faster.