The L337WHH6 is an white PP plastic 38-400 child-resistant lid with a heat induction seal (HIS) liner. This closure includes a HIS liner with a two-piece pulp backed heat induction foil innerseal that will provide a tamper-evident bond to polyethylene containers. Please read 5 seals and how they make perfect liners for your container for more information on liner types. 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 38-400 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.