Our divider cards are professional heavy duty store grade divider cards. They are made of 100% virgin High Impact Polystyrene (HIP). They're the strong stuff - it's what we sell to music stores all over the country! These cards are rectangles with rounded corners - it eliminates jabbing yourself on the sharp corners! We believe these to be superior to the "tab" style dividers because those are more likely to snap off These dividers are reusable - if you don't need that section anymore, just turn it around or turn it over! =) CUSTOM SIZES AVAILABLE!! We now manufacture all divider cards in house! We can make any size divider card up to 48" x 54" in size. Please contact us for more details!