These gold polypropylene plastic caps are available in a variety of sizes and come with PE (F217) liners. The PE liner is a good general-purpose liner material. It has a broad application base and chemical resistance making it a good choice for many acids, alkalis, solvents, alcohols, oils, household cosmetics, and aqueous products. The plastic caps are also ribbed to give the user better grip when twisting the cap on and off.