The ruler was super simple and fast to make 8 hsts at one time. Each one was perfect except the two I sewed off the sewing line a little. LOL I was in a hurry. The math is all calculated and the charts are matched to the ruler markings. No bias on the outside edges. It's easy to make any size finished HST you need. I used two charm squares to get eight
2" hsts that will finish at 1 1/2" I did not have to square up!