I missed this in April but Math-U-See has changed the binding and look on their books. Our spiral bound books did get a little beat up towards the end of the year so I'm happy to see the new binding - especially with perforated pages which would allow us to file lesson by week in a file folder (something I toy with frequently). However! I didn't notice all of this prior to my purchase because I was lured in by the idea of a Math-U-See Clearance area. Ahhhh, clearance! So I ordered a copy of the older Delta set which was discounted. I do look forward to the trying out the new binding with Epsilon, but for now I'm happy to have a saved a few dollars in the book budget.