Each Tessera Book comes with 42 pages which fit perfectly on our screw posts. You can add one or two Tessera Insert packs to your book by removing the cardboard spacers in the front and back of your book. If you add more than three insert packs to your book, you will need screw post extensions. Contact Customer Service at (888) 454-0094 or email customerservice@tesserapublishing.com and we will send you what you need.