All surfaces of the Argos 250mL tissue culture flask come treated. Flask surface is flat and free from striation to maximize useable growth area. Vented polyethylene caps contain a 0.22 hydrophobic filter to allow gas exchange and minimize the risk of cross contamination. Sterilized by gamma irradiation. Certified non-pyrogenic. Cap material: polyethylene. Flask size: Argos #: F1225.