Flask Filtering 250ml., Conical, with integral side arm, Glass Connector-EIS-CH0420B offers a thoughtfully designed, durable resource for hands-on learning. 250ml Filtering flask High Quality Borosilicate glass Filtering flask with integrated side arm adaptable to 3/8" internal diameter tubing (1) Single Flask 250ml with 50ml graduations EISCO Filtering Flask, 250ml, borosilicate glass ( Single Flask) 50ml graduations with integrated side arm. Made with High Quality Borosilicate glass 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. Eisco Labs proudly manufactures its own products using state-of-the-art equipment, and following the highest standards of quality control. Each product is carefully designed by a team of laboratory professionals and experienced engineers with quality and durability in mind. They are manufactured with only the highest grade, raw materials and according to international quality standards to ensure that they can withstand use in even the toughest laboratory environments.