Lab silicone Stoppers, White Tapered Plugs for Chemistry Flask & Test Tube
The tapered plug is in size : 4# / 5# / 6# / 7# / 8# / 9# / 10# / 11# / 12#. Conical design, solids, easy to install and good sealing performance, flexible and durables, not easy to crack, shrink, harden or break.