This Eisco Labs Test Tube has a 20mL capacity with a flat bottom and is constructed from high-quality borosilicate 3.3 glass. The tube measures 2.8" tall and 1" in diameter and is fitted with a Bakelite screw cap for a secure seal. The flat bottom allows the tube to stand upright without a rack, making it convenient for sample storage and display. Borosilicate glass provides excellent chemical durability and thermal resistance. Suitable for storing, mixing, and heating small volumes in laboratory and classroom settings.