1. silicone 2. Material: The silicone containers Is Made of BPA-FreeFood-Grade Silicone Material, Which Is Corrosion-Resistant, Odorless, Soft And Non-Deformable, EasyTo Clean, And Can Be Used Repeat At high And Low Temperatures (-60~450¡ãF) 3. Size: Food Storage Containers Size: 8.663.347.92.766.92.175.81.77 Inches; capacity: 71oz2100Ml, 44oz1300Ml, 23.6oz700Ml, 20oz300Ml. 4 Sizes Can Be Stacked For Rasy Storage. 4. Purpose: 4 Containers Of Different Colors And Sizes Have Scales To Meet Different Usage Requirements. They can be used as Meal-Prep Containers, dry food storage, Refrigerator Preservation, Snack Boxes, And Fruit Boxes. The inner Surface is Smooth, they are zer and can be used in the oven and sterilized in boiling water. 5. Function and suit: The Food Storage Containers with Lids has four colors of Red, Yellow,Blue, And Green. It is thick and flexible. The color is novel and easy to distinguish.These food containers are designed with liquid volume markers to make meal prep easy and convenient, plus it's easy to stay organized. Simply use dry erasers or chalk markers to make a note on the silicone and remove it with a wet tissue or warm water and soap.