Falcon™ Primaria™ Cell Culture Flasks are made of surface-modified polystyrene for enhanced cell culture. Canted neck, blue plug-seal screw cap. Falcon™ Primaria™ cultureware features unique nitrogen containing tissue-culture surface chemistry that improves attachment, spreading, and growth for many primary cells or cell lines. No special storage required. Sterilized by gamma irradiation, nonpyrogenic.