Aluminum: It has an internal coating so that the water does not come into contact with the metal. It is lighter, suitable for younger children, and usually more affordable.
Stainless Steel: It is an inert material. It does not require an internal coating. Even if it gets scratched inside, there is no risk of chemicals leaching into the water. It does not retain odors and is usually double-walled and insulated.
Plastic Tritan: Tritan is a durable BPA-free plastic, ideal for everyday use and safe for food.
Silicone: It is a completely safe and healthy material, free of harmful chemicals. It is ideal for children because it does not break if dropped, is very lightweight, does not retain odors, and is extremely easy to clean (even in the dishwasher).