These black polypropylene plastic caps are available in a variety of sizes and come with PE F217 liners. The PE F217 liner is a great general-purpose liner and has a broad application base, and chemical resistance. These caps may make a good choice for products such as acids, alkalis, solvents, alcohols, oils, household cosmetics, or aqueous products. The polypropylene PE F217 lined closures also feature a ribbed exterior for a better grip when twisting the cap on and off.