The water bottle is made of food grade 18/8 stainless steel, and the cap is made of plastic and silicone. Double-walled construction and vacuum insulation keep drinks cold longer. Condensation will not form on the outside of the insulated bottle, avoiding water rings and slippery sides. The screw cap has a silicone gasket so it won’t leak, and the silicone band on the outside helps with grip to make sure it’s tightly closed. The cap is attached to the water bottle with a strap to prevent it from getting lost.