KIMAX® 6000mL Florence flasks have a low coefficient of expansion to resist thermal shock. They are constructed with sturdy walls to minimize mechanical breakage, and reinforced tooled tops for strength and a secure stopper fit. Designed from ASTM Specification E1403, Type I, Class 1, requirements. Accepts #11 rubber stoppers. 1/Case. Kimble® #: 25000-6000.