There are 2 versions of Wool on Audible — "Wool Omnibus Edition (Wool 1 – 5)", collecting books 1-5, for $ 16.16 (or $ 7.49 if you also buy the Kindle Edition); and "Wool (Silo, #1; Wool, #1-5)", also apparently collecting books 1-5, for $ 1.99 if you buy the Kindle Edition. https://mobile.audible.com/pd/Sci…B00C7R2NQ8. If you follow the Audible link to buy the Kindle Edition of "Wool (Silo, #1; Wool, #1-5)" on Amazon, it takes you to Wool #1 on Amazon — the first book of the series that is 58 pages and is free. Buy that free book and add the Audible version to your purchase for $ 1.99. That will add "Wool (Silo, #1; Wool, #1-5)" to your Audible library. That Audible book says it has all 5 books, and the narration is over 17 hours – like the "Omnibus Edition". I haven’t listened to the whole book yet, but it contains 83 chapters and starts by saying you are listening to "Wool Omnibus Edition", so this appears to get you all of Wool on Audible for $ 1.99.