I have an alternative version of this, where the lining is on the outside of the pocket! This was a mistake, so is slightly discounted :). You can see what it looks like in the pictures!
 
These book sleeves are made using cotton fabric.

They have a button elastic closure to keep your book secure inside.

They fit standard size UK paperback books (19.2cm x  12.7cm)  up to 900 pages long, it's a bit of a tight squeeze for books that are 900 page size, but they do fit :). Because they can fit books that large, they can alternatively fit 2 smaller paperback books inside!

They do not fit hardback books (unless they are smaller hardbacks, the same size as paperbacks) but I am planning to make ones that fit hardbacks in the future!

Each sleeve has a layer of wadding inside, to add a little cushion protection to your book!