The L336WHF1 is a white lid made from polypropylene (PP). The lid fits containers with a neck finish of 28-400. The lid includes a foam liner which will create an air-tight seal when the lid is securely screwed on. This lid is child-resistant making it ideal for packaging pills or other potentially hazardous products. Please read 5 seals and how they make perfect liners for your container for more information on liner types.