I started with a 2 – 3 holder and had requests for more sizes so have added 4 – 5 width (binder size). These are great! Binders require some way of labeling and this was always a problem for me until I found these. You ll love them too! They are sticky and mount to the outside of your binder. Then, you fill out the enclosed paper insert and put it in the slot. You can always make other labels using color coding, etc. A great way to organize your photos, research etc.