Black polypropelene shelf liners allow you to store small and unstable items on wire shelving by providing a flat surface. Our quality liners are made by Chadko, LLC., a small, woman-owned business in Western Michigan. The .635 mm thick polypropelene (a type of plastic) is black. It is water resistant and can easily be wiped clean. Not suitable for use as a work surface. Sold in a 4 pack. Note: This item is shipped rolled in a tube for eco-friendly shipping. It fully flattens after a day. Actual Dimensions: 17.3125" x 29.0625" x 0.025"