These 125 mL PYREX® wide mouth Erlenmeyer flasks are especially recommended for use as titration flasks and are designed with heavy duty rims to reduce chipping. For convenience, these flasks are graduated in durable white enamel to show the approximate capacity and have an extra large marking spot. They require a No. 6 rubber stopper for sealing. Their uniform wall thickness provides the proper balance between mechanical strength and thermal shock resistance.