Flask Conical 250ml, wide neck, borosilicate glass-EIS-CH0426B offers a thoughtfully designed, durable resource for hands-on learning. High Quality Borosilicate glass 250ml Capacity with 50ml graduations This flask has a 5.5" height, 1.75" interior diameter at opening, and 3" diameter base 1 Single Erlenmeyer conical Flask 250ml, wide neck, Made from high quality borosilicate glass. 250ml with 50ml graduations. This flask has a 5.5" height, 1.75" interior diameter at opening, and 3" diameter base. Eisco Labs Borosilicate glass has the following heat tolerances: Strain Point -515°C | Annealing Point 565°C | Softening Point 820°C.