The inside of the bottle is made of 304 stainless steel, while the outside is made of 201 stainless steel.This extra-large vacuum water bottle is perfect for travel, family gatherings, and more. It can keep your favorite beverages cold for up to 12 hours and hot for up to 10 hours. Totally no leak! You can print your brand logo or any content on the outside of the bottle. Hand wash recommended for the best product care.