Thermal Resistance, Hygenic & non porous surface, Transparent borosilicate glass lids. 25 year guarantee against manufacturer defect.Can be used in/on any kitchen appliance (except induction). Does not stain or retain flavours. Can be used straight from the freezer to top of stove or oven. Freezer, Dishwasher, Microwave and Oven Safe. Stylish enough to take to the table.