The PKCS045K is a black smooth non child resistant certified cap with a neck size of 45MM. This cap has a HS035 foam liner (HS035 is an induction seal liner and is used with induction sealing equipment. A thin layer of liner material is electromagnetically activated by the induction sealing machine). This has a backing thickness of .020 and has "sealed for your protection" in red on the to of the liner. This is a universal liner and works with both glass and plastic bottles. This is used for dry products, milk, peroxide, fruit juice, glass cleaner, spices and nutraceuticals. Not good with oil or solvents.