Silicone is one of the most inert and non-reactive materials available today. That’s why we use it as the seal in the humangear stax lids. However, as great as silicone is, all silicones can react with some fluids and chemicals. So, the silicone seal used in the humangear stax lids may not be compatible with all ingredients, specifically some found in beauty and cosmetic products. For more information on silicone compatibility, see the Compatibility Page for the GoToob+

Features:

• BPA- and PC-free polypropylene containers meet FDA requirements for food-safe storage
• 180° twist mechanism is easy to open and close even in cold weather; there's no wrenching the lid down to ensure a full seal, so they remain easy to open even with gloves on
• Silicone lid gasket ensures a watertight seal
• Containers stack together for portability but easily come apart for modular storage; lids attach to any interlocking base, making it easy to take just what you need
• Rounded container bases don't have sharp angles, allowing for easy cleanup
• Cylindrical shape slips into pack and water bottle pockets easily
• ClipHandle securely attaches to a backpack
• Backed by the manufacturer's unconditional lifetime warranty