The L463SLF1 is a silver aluminum over shell and white plastic 70-400 smooth skirt lid with foam liner. This cap is made of polypropylene and has been affixed with an aluminum shell. This closure includes an F217 foam liner, which will create an airtight seal when the lid is securely screwed on to the container. This lid is made of polypropylene (PP), which means it has a high heat tolerance level and an excellent resistance to fatigue. This closure fits a container with a 70-400 neck finish. The first number refers to the diameter of the container's opening (in mm). The second number refers to the thread/style/depth of the closure's skirt. Please read 5 seals and how they make perfect liners for your container for more information on liner types.