The L111PF is a white PP plastic 20-400 ribbed skirt lid with an F217 liner and a pressure sensitive (PS) liner. This closure includes an F217 foam liner, which will create an airtight seal when the lid is securely screwed on to the container. This closure also comes with a pressure sensitive (PS) liner. Pressure sensitive liners are made from foamed polystyrene. When the cap (with liner installed) is affixed to the bottle, the liner adheres to the bottle's landing/orifice. Before product can be dispensed, the lid must be removed, and the PS liner peeled off and discarded. 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 20-400 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.