 archival paper i don't know it just does that once in a while once we know i'm there uh they have gold gold lettering gold leather bound they're beautiful they're beautiful they're just beautiful books they're built to last forever uh they're not going to fall apart on you after you know 50 or 60 or 100 years however long you happen to have this book for but these are a complete set uh not a complete set they're about 80 in the complete set he had 64 of them