This is that really hard plastic that my mom always called Styrene. I don't know if it's really that stuff, it just feels like it. The lid is a little fiddley it opens on tracks and it's kind of easy to pull off it's track. Now, that being said, they are the right size and shape to hold loads of cricut cartridges and booklets with overlays. They truly are just right. How well they hold up and how well the top works over time, we'll see. I'm glad I got them (I got three of different color lids) and will try to use them to their full extent.
I was disappointed in the quality of the case. The sides seem a little unsturdy when you try to snap the lid in place, and the lid doesn't seem to fit that well. I plan on using them in my home and do not plan on transporting them back and forth to a scrapbooking event.