The L240FB is a black ribbed lid that includes a foam liner, which will create an airtight seal when the lid is securely screwed on to the container. This lid has a neck finish of 70-400. The L240FB is made of black polypropylene (PP) which has a high fatigue resistance and heat tolerance. Please read 5 seals and how they make perfect liners for your container for more information on liner types.