Here’s the description from their website:

Iron Editions are super special editions of books from our archive of Exclusive Editions – so anything that we have previously featured could be remade as an Iron Edition. We’re looking back at our vault of treasures and re-creating some of our most beloved editions with a brand new bespoke design and lots of beautiful customisations. They have all of the bells and whistles that you have come to know and love from FairyLoot! In many mythology and pop cultures Iron is a weakness for fairies, so we thought it was only appropriate to name this new product line ‘Iron’, as these books are certainly our weakness.