- Premium Quality Material: Glass bowls are made of heat resistant high borosilicate glass, lead-free, and more sturdy and resistant to breakage than cheaper glass. The lids are made of food grade PP material and BPA-free. - High Temperature Tolerance: These bowls tolerate -4 F to 1040 F and are microwave, oven, fridge, freezer and dishwasher safe (lids excluded from the safe-use note). - Airtight Seal Lids Design: Each bowl comes with an airtight lid; portable and easy to seal, keeping food warm and fresh. - Space-Saving Storage: The nesting design allows the kitchen bowls to stack neatly inside each other, saving shelf and cabinet space. - Use scenarios: - Meal prep and serving: mix ingredients, portion snacks or salads, and serve directly at the table. - Leftovers and storage: store in fridge or freezer with the airtight lids; reheat in microwave or oven as needed (lids not used during heating). - Kitchen organization: stack and store compactly when not in use to maximize smaller kitchen space.