These containers are made from BPA-Free Polypropylene that is extra durable, extra strong and can withstand far more rigorous circumstances than their disposable counterparts, making them ideal for repeated use. They are microwavable, dishwasher safe, and fully recyclable. The clamshell style container has an attached lid with snap-latch to keep containers closed, and food contents secure. These containers are very stackable, both for organization in the fridge, cooler, and also in the cupboard.