Pennyhead Stopper, Solid Glass 24/40, 1 Each

The Pennyhead Stopper, Solid Glass 24/40 by United Scientific is a solid-plug borosilicate 3.3 glass stopper with a sealed bottom, a vertical penny head and a taper-ground 24/40 inner joint. It closes flasks, graduated cylinders and funnels that have a matching 24/40 outer joint, and the glass conforms to ASTM E438 Type 1, Class A. Chemistry teaching labs, analytical labs and synthesis groups use it as a reusable, solvent-resistant closure, and it is sold individually.