They are a nice weight of cardstock. They were easy to assemble, hold their shape well, and hold up to sliding in and out of shelves. I bought these to go into the shelves of a ClosetMaid 8953 Stackable Vertical Organizer. Three of them fit in each shelf. I had to trim the tops down to the correct height, which is easy to do, and it looks great. I needed a simpler filing system on my desk and didn't like any of the desk organizers I found, so this was my DIY solution. So far it's working really well.