Borosilicate, with penny head Conforms to ASTM Standard E 675 Size Standard Taper 13 has solid plug; size Standard Taper 38 has recessed bottom Standard Taper designation indicates the approximate diameter of the ground zone at its widest (gauging) point.

These blue and white No. 16 PYREX® stoppers are made from linear high-density polyethylene and have closed bottoms to conform to Standard Taper stopper dimensions. The three rings on the plug provide an efficient seal. This improved design fully protects the neck in the event of accidental…

These chemically resistant PYREX® keyhole stoppers are made from polytetrafluoroethylene (PTFE) and conform to Standard Taper stopper dimensions. The color-coded keys make sorting and selecting the correct size much faster and easier. These stoppers may be used in place of conventional glass…