Borosilicate glass stopper with hexagonal head for improved grip. Cone Size: 14/23. Overall Height: 56mm. Ground glass stopper supplied in European 'B' length joint sizes, making them suitable for use with any jointed glassware products with the same joint size. Ideally suited for use with Quickfit® jointed glassware and other glassware having ground glass joints. Complies to ISO 383 standard tapers. Borosilicate glass for chemical durability and high temperature performance. Hollow blown construction to reduce weight. Hexagonal head prevents the stopper from rolling and provides good grip. Top of the stopper is flat, allowing them to be stood on end and avoid contamination of the ground surface.