Nunclon® treated polystyrene tissue culture flasks provide a hydrophilic surface for optimum cell attachment with high optical quality. Large necks provide easy filling and pipet access. All Nunc flasks have interlocking rims and volume graduations. To limit growth to specified areas, flask necks are not treated. Phenolic caps can be spun on or off to reduce production operation time. The polyethylene plug-seal caps vent to allow air exchange through a labyrinth or close to maintain an air/liquid tight seal. All flasks are supplied sterile with caps.