Material safety. BPA free, containers are made of 100% food grade polypropylene and silicone: non-toxic, environmentally friendly. Super smooth surface on the inside to avoid grease and very easy to clean.Ingenious design.Lid with 4-way click closure, leak-proof silicone sealing ring. Small valve at the top of each container to release water vapor. Allows for easy, compact storage, folds to 1/3 of its original size, saving more than 60% space.Foldable. Rectangular food containers for meal preparation can be folded to 1/3 of their original size. The nest design ensures maximum organization. Fits in almost all kitchen and storage compartments or in cupboards or drawers.Ideal food storage.Perfect for food storage. Easy to assemble and carry, it is the best lunch partner for children, but also ideal for adults to develop healthy eating habits, and an ideal choice as a gift.Easy to carry.