Stackable bento box. Modern and compact design. Features a space saving atackable attribute to present a simple, crisp, modern look. Excellent for portion control and balancing meals. Not intended for large portion meals. Made with high quality food safe materials: food grade polypropylene, silicone, ABS plastic, and BPA free. Extremely easy to wash and store away. Freezer safe, dishwasher safe, microwave safe. When microwaving with inner lid, please open ventilation plug. The airtight silicone sealing ring on the lid prevents leakage and spillage for a mess free, clean way to pack lunch. However, it is not waterproof so please pack liquids or soups in a separate container. Due to secure strong sealing, if it gets tight to open, please set it flat and open the ventilation plug gently to let pressure out then open the lid. Hand washing recommended to maintain and preserve the leakproof seal lids and longevity of the product.