“Overs” are overrun copies of a book produced during a print run with an offset printer. In offset printing, it’s industry standard to have +/- 10% variability in the final number of books printed, compared to the number of books ordered. Since large rolls of paper are used for printing before folding, trimming, and binding, they have to do a materials estimation (since the printer may have to run calibration on the press before the printing comes out just right). The press can’t be stopped at a certain number of copies—it runs through the materials. This, along with the amount of calibration needed, can either create a surplus or shortage of books, not to exceed +/- 10% of the quantity ordered.