We partnered with Miir to offer a water bottle that stands up to the same abuse as our bags and apparel. Built to endure.Constructed from 18/8 Medical Grade Stainless steel, this 23oz bottle is guaranteed to be water tight. The Vacuum bottle keeps contents cold for 24+ hours and hot for up to 12 hours. The bottle fits perfectly in out Arkiv side accessories or just stash it in your bag.Thermo 3D (TM) Double Wall Vacuum Insulation Technology Stays cold for 24+ hours and hot for up to 12 hours Does not sweat BPA free One twist lid Perfect Seal(TM) Engineering 18/8 Medical grade stainless steel Hardshell(TM) Powder coat (colored bottles) Optimal size opening