borosilicate glass, tube capacity (18 mL), beaded rim, tube diam. (16 mm) , External Thread. Expand. Hide. DWK261312107. borosilicate glass, tube volume (18 mL), straight rim, tube diam. (16 mm) , External Thread. Expand. Hide. DWK2613 4. borosilicate glass, tube volume (20 mL), straight rim, tube diam. (20 mm) , External Thread.