Agung Universal Bonza Pyrex Tough Down Stem. Turn your metal stem bonza bong to a modern Pyrex Tough glass stem cone bong, by using the universal bonza glass stem. This stem fits all Bonza sized connections for all agung bongs. The connection with the glass cone is standard 14mm joint size. The length is 18cm including the connection part. If it is too long for your bong, you can use a glass cuter to make it shorter. The rubber grommet is included.