Made of high quality, heavy duty, Borosilicate 3.3 glass 5ml capacity, single, white graduation mark ASTM, Class B, ±0.040ml tolerance Fitted with a #9 glass stopper Stands 3.6" tall, and is 0.9" in diameter at its widest point. Neck outer diameter measures 0.5" 5ml capacity volumetric flask made of high quality, heavy duty Borosilicate 3.3 glass. Single, white graduation mark. Blue printed specifications. ASTM, Class B tolerance, ±0.040ml. Fitted with #9 glass penny stopper. Flask stands 3.6" tall, and is 0.9" in diameter at its widest point. Neck outer diameter measures 0.5". Autoclavable, with superior chemical durability. Low temperature gradient- can withstand high temperatures & thermal shocks. Eisco Labs Borosilicate glass has the following heat tolerances: Strain Point -515°C | Annealing Point 565°C | Softening Point 820°C.