Glass stopper,cap design,ground interchangeable taper outer joint,used to fit 24/40 ground inner joint.The frosted, precision-ground glass surfaces make a good seal when properly greased .
The outer joint has a taper, it can fit any glassware with inner joint which has the same taper and same outside diameter as long as the apparatus to which they are attached does not interfere. For example, a joint stopper with 24/40 outer joint will fit into a 24/29 flask.
This cap design stopper is made of high quality borosilicate glass 3.3 by hand-blowing,the glass tubings we used for hand-blowing are heavy wall design.