This PYREX® gas dispersion tube with fritted cylinder have a coarse porosity (40 to 60µm) fritted cylinder and are used to disperse or scrub gas in liquids. The size of gas bubbles depends upon the porosity of the fritted cylinder and the liquid used. The finer porosity discs give smaller bubbles, however greater gas pressure is required. The 12mm O.D. fritted cylinder permits insertion through small openings. Dimensions:(H x Stem O.D.) 250 x 8mm. Disc Diameter.: 12mm. Porosity: Coarse. Material: Borosilicate Glass Code 7740. Corning® #: 39533-12C.