This is the pinnacle of book binding! You will have most likely seen it on a coffee table photo album style book. Each spread of pages is printed on a single sheet of paper, and glued to the preceding and following pages. This means you have no centre spine to interrupt artwork. This is very popular for any high end book that needs the best possible presentation. It can have a fancy case bound cover, or the cover can be the same weight as the pages. The finished weight of each page is usually at least 400gsm, because the paper needs to be thick enough to carry enough glue without distortion. The result is a premium book that opens flat and allows artwork and text to carry across the centre of the page without any alignment issues.