2 Part Invoice Books contain 100 Sets/Book*, 3 Part Invoice Books contain 50 Sets/Book* All books come with manilla cover, cardboard backs and wrap around writing shield. All books will be numbered and perforated to your specifications. Our Invoice Books contain 100 duplicate or 50 triplicate sets, the top set is printed onto white page and is perforated to remove for the customer, the bottom set is printed onto yellow paper and is fixed into the book for your file copy. Invoice Books – they are self carbonating and also can have sequential numbering so that you can easily refer back to your file copy if required.