The L475WHF1 is a white PP plastic 89-400 smooth skirt lid with foam liner. This closure includes an 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 89-400 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.