When you like to be the best, nothing less will do. Borosilicate glass makes it safe for use in microwave and conventional ovens, and also in freezers and refrigerators. Highest quality glass and technology makes it explosion proof and safe for use. Borosilicate glass will not leach any chemicals into food even at high temperature heating. Package contents: 2-pieces lunch box (320ml), 1-piece lunch box (530ml) and 1-piece lunch box (900ml).