I need to mail CDs to friends and saw these. I was a little leary at first because they seemed flimsy and bendable but once the CD is inside it's pretty rigid. No complaints of broken CDs yet from recepients. The one downside is the shape. Because it is square and thick it does not qualify as even a "large letter" by USPS standards so you will pay the 1st class parcel rate of $2.07 for the first 3 ozs as opposed to about $.83 for an oversize letter. You need to factor that into your overall cost analysis. I will probably be looking for another CD shipping solution once these run out.
I have a ton of used books and am trying to declutter. I've been selling the books and use these Bubble Wrap mailers get them to customers in great condition. They're also a snap to use since I just have to remove the strip on the flap and press it down to close the envelope. The mailers are also very sturdy so I don't have to worry about the sides coming unglued and the book slipping out. The books are getting to my customers in great shape. I would definitely recommend these to anyone.