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 female joint has a taper, it can fit any glassware with male joint which has the same taper and same outside diameter as long as the apparatus to whic/h they are attached does not interfere. For example, a joint stopper with 24/40 female 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.