PYREX® Narrow Mouth Heavy Duty Erlenmeyer Flasks have approximate graduations in durable white enamel. An extra large marking space is also provided. Heavy, durable top tooling. Convenience pack contains one each of five sizes: 50mL, 125mL, 250mL, 500mL and 1000mL. Packaged in a partitioned carton for safe transit and storage.