Black, ribbed continuous thread cap with 20-400 neck finish and a .035" F-217 foam liner. Commonly used for household, cosmetic, food and beverage, liquor and other water-based products. Continuous thread caps are popular in a wide range of wholesale industries from food, personal care, pet care, household products, industrial products, health and beauty, arts, crafts, hobbies and just about any other market segment. This polypropylene (PP) cap has a high tolerance for heat and is very durable. Liners are an important aspetc. of every continuous thread cap and products should best tested with the cap to determine which liner will be the best fit. F-217 liners are made of three layers, a thin foam core is placed between two layers of LDPE film. While F-217 liners are commonly referred to as foam liners, they tend to perform better than a regular foam liner. F-217 and foam liners do not create airtight seals.