Enough long drawer divider trays to fit the shelves in your refrigerator.
Before you head to the store, measure the width and depth (front to back) of your shelves to make sure you get enough containers for your fridge. The ones I found were 16 x 6 x 2.04 inches. As you can see in the photo to the right, they have little rubber pads on the bottom to keep them from sliding around in a drawer. Our daughter’s shelves were coated wire so they worked well. If you have glass shelves you might need to remove them for ease of sliding them in and out to access what’s in the back.