1000ml Volumetric Flask Made of Class "B" borosilicate glass One graduation mark Fitted with chemical resistance polythelene stopper. 1000ml Volumetric Flask made of Class 'B', Borosillicate glass with one graduation mark. Fitted with chemical resistance polythelene stopper. Calibrated to contain. 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.