Sip in style with the Hydro Flask Standard Mouth 21oz bottle in black. Using double wall vacuum insulation, the TempShield™ technology prevents condensation and heat transfer—keeping cold drinks icy cool and hot ones piping hot for hours. The 18/8 pro-grade stainless steel construction is durable, long-lasting, and provides pure taste with every sip while the proprietary powder coat finish ensures slip-free grip. With a convenient loop on the Standard Flex Cap lid, this water bottle is easy to carry and great for those on the go, whether camping, hiking, at the gym or just working in the garden.