These reusable ice cubes are made with a non-toxic purified water and may require 48 hours to freeze. They can be used anywhere you would typically use ice but are not recommended for direct food contact. The reuseable ice cubes are better than traditional ice - no water mess to clean up. Another key feature is that they will stay cool 30% longer and cold for up to 8 hours. These reusable ice cubes are easy to maintain - just wash with mild soapy water after each use and then refreeze.