Airtight Lockage Space Saving Design Passed the strict hygiene and safety tests of U.S. FDA and German SGS OK & Sterilization in hot water OK, Freezer Ok Passed the leakage tests by authoritative local and international institutes. 4-sided locking system of lock and lock makes it possible to be airtight due to equal pressure to all 4 sides 2-1/2-Cup/20-fluid ounce Made of high quality BPA free plastic Airtight seal with great elasticity power locks tightly with hollow-center silicon Microwave, freezer, and top rack dishwasher safe