Most bookcases sold today are lightweight and not all shelves can hold books. Top shelves should be covered with light material to prevent tipping. These spacers help tilt the bookshelf against the wall to minimize the chance of collapsing. That doesn't change the fact that nothing heavy can be placed on the top shelves, but overall the shelves are safer to handle. The pads are the best I've found, matching the color of hardwood floors, darker tile, and carpet.
38-Piece Non Slip Furniture Pads Grippers For Hardwood Floors - Self Adhesive Rubber Feet, Anti Slide Protector To Keep Couch Stoppers In Place
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32Oz Gorilla White Waterproof Patch & Seal Liquid For Effective Sealing (Single Pack)
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