The term “leakproof” applies to Thermo Scientific Nalgene products that meet the following criteria: a) Bottle/flask/funnel closure systems with closures smaller than 100mm, after they are filled with water, inverted, withstand air pressure of 2psig for 2 minutes, and no water escapes;. B) Bottle/funnel/flask closure systems of larger than 100mm after they are filled with water, inverted for 15 minutes, and no water escapes. Note: these tests, using other liquids, may not yield the same results. To ensure safe usage, customers are advised to test Thermo Scientific Nalgene bottles and closures under conditions of their planned applications. Thermo Scientific Nalgene products are leakproof at ambient temperature and pressure when used with their Nalgene closures.