Basics

A Method of Optical Disc Packaging
Typically made of Polystyrene although Polypropylene versions are available
It is a hinged design made of seperate pieces
- Allows for repairability
It has slots for paper cards to be put for labels
Most Music CDs are sold in Jewel Cases unless they are in a cardboard sleeve etc

Sourcing

"Super Clear" seems to be a marketing synonym for this
If being overly cautious if not listed it probably is PS as well, although if i get that Plastic Scanner sometime can mess around and see
- That or if consumer websites like Amazon would actually have all the damn information and lay it all out for you!
AcePlus - Premium Single Disc Jewel Cases in Super Clear with 10.4 mm Standard Thickness Assembled (10-Pack) (~24 USD)
Maxtek 10.4 mm Standard Single Clear CD Jewel Case with Assembled Clear Tray, 25 Pack (~25 USD)

The Wikipedia Page on Jewel Cases
WeWow Ltd - Plastic CD/DVD Packaging - Polystyrene vs Polypropylene (Doesn't seem that great of a source upon further inspection, will leave it regardless]
- Accelerated Aging Tests of Plastics and maybe a glance at their various "strengths" /
- Quick check, and at least as per This Page by "Omnexus" Short of High Impact Polystyrene and various reinforced composites, Polypropylene should be stronger, at least in the quantitative data Charpy Impact Test / Izod Impact Strength Test
- Granted as per This Xometry Page it seems that without knowing the "secret sauce" it can very quite a bit. Still though outside of optical clarity it seems with the right selection Polypropylene would still win out.