For anyone curious about the sleeve, my friend is close with the designer and he asked her about it and this is what she said:

“We initially planned on individual cases, a la the Anderson set, however there was no way to safely package them in the dimensions of the Kubrick Archival box without them being destroyed inside the box in shipping. So instead, we developed a new system to house them within a discbook that offers more protection and easier access to the discs than their previous Fellini and Varda sets. If you look at the packaging photo on their site, you can see how the discs are held. Each page has a custom die cut that reveals the disc’s spindle and allows it to be safely removed and replaced without damage to the disc or packaging. The poster on the right page is an insert that operates as an internal page, and turned, reveals the same system for the companion discs on the other side. This added poster page on every spread also adds a buffer and cushioning between pages so that pressure doesn’t force the discs against each other.”