Clear vials offer maximum visibility. Made of type i borosilicate glass, providing exceptional resistance to heat shock and chemical leaching. 27.75 x 95 mm, 10 dram (40 ml) Clear borosilicate glass vial with 24-400 neck finish. The glass is non-porous and has no catalytic affect. Because the boron oxide particles in the glass are so small, the silicate is held more closely together, resulting in a much stronger glass for your laboratory needs.