Hard / Protective Book Cover / Case for the Paperback ??

I have an old copy of HoL that has been well loved and well read by myself and some friends.

I was looking for a protective book cover and all I can seem to find are the fabric stretchable ones.

Has anyone purchased a more protective one for their paperback?

I'd like to find something for mine as I am about to dive in to it again. You always find those things you missed on first read through's, especially in my case when it was like 20 years ago.

Thank you!