Hydro Flask 21 oz Standard Mouth w/Standard Flex Cap Stone, Summer - Hydration - Hiking bottles, Unisex 2021 Hydro Flask stainless steel water bottles are perfect for those looking for a water bottle made of durable, recyclable and healthy material. They are guaranteed for life. The advantage of stainless steel is that it gives no taste to your drink. 18/8 stainless steel is an ideal material for food, especially drinks. Thanks to its double wall and insulated cap using TempShield technology, the Hydro flask will keep your drink cool for 24 hours and your hot drink hot for 12 hours. This Hydro flask is very strong and resistant due to its composition and construction. Compatible with the Hydroflask sports cap TempShield insulation to eliminate condensation. Keeps the heat for 12 hours and the freshness for 24 hours. Constructed of durable 18/8 Pro-Grade Stainless Steel BPA and Phthalate-free Capacity: 621 ml.