These plasma-treated tissue culture flasks are made of high-quality polystyrene for optical clarity and distortion-free examination The vacuum-gas plasma treatment ensures a consistent growth surface providing optimum cell attachment and maximum yield. Straight-neck and canted-neck flasks are supplied with a choice of plug-seal caps, for use in open or closed incubation, or rigid, phenolic lined caps that spin on. All flasks, except for 291-7 and -, have a frosted writing area to make labeling fast and easy. Graduations are easy to read in a hood. Flasks are sterilized by gamma irradiation and nonpyrogenic. Ordering information: Accessories not included.