I don't always buy the heavy duty binders. They are expensive, and we use a lot of binders in my office. But I do notice that it is the Avery heavy duty binders that I am always looking for when I reuse older binders. I often reuse binders, perhaps those that were handed out at a conference many years ago. Avery Heavy Duty binders really are durable, and the D-ring is easy to use and allows pages to lie flat, so they are less likely to develop that permanent "curve" that can occur when pages are in a binder for a long time.