HydroFlask Hydro Flask 21oz Standard Mouth Bottle Double wall vacuum insulated stainless steel water bottle keeps drinks cold for up to 24 hours and hot for up to 12 hours Premium grade 18/8 Stainless Steel BPA free Sports Bottle High quality colorful powder-coated matte finish exterior that never sweats A great way to give back Hydro Flask donates 5% back to a charity of your choice The Lifetime Warranty makes Hydro Flasks the best water bottles