Polypropylene open-top caps and Teflon/silicone septa Useful in volatile organic analysis Of high-quality borosilicate glass Available in clear or amber Four classes available: 10 Class: Container, cap and .010” Teflon ® capliner. 1000 Class: Container, cap and Teflon/silicone septa or .030-inch Teflon capliner. 2000 Class: Container, cap and solid Teflon capliner or septa; EPA pre-cleaned