The L252HI-456 is a black PP plastic 89-400 smooth skirt lid with 2-piece printed heat induction seal (HIS) liner in bulk packing. Bulk packing means that all lids are loosely packed in one case. This closure comes with a heat induction seal (HIS) liner, already placed inside the cap. An HIS liner is a metallic disk that provides an airtight, tamper-evident hermetic seal when an appropriate heat induction sealing process is applied. This liner can work with plastic or glass containers. For more information on heat induction sealing and available machinery, please read our article, How to use HIS liners and a heat induction sealing machine. This liner has been printed with a "sealed for your protection" (or similar verbiage) notice. 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.