The Ozizo 20 fl oz (590 ml) Double Wall Vacuum Protein Shaker Bottle is a high-quality and durable flask designed to keep your protein shakes and other beverages at the desired temperature for longer periods. The double-wall vacuum insulation helps to maintain the temperature of the liquid inside, while the small mouth design makes it easy to drink from and prevents spills. The stainless steel spring ensures that protein powders and other mix-ins are properly blended with the liquid, and the bottle is easy to carry and handle thanks to its compact size and lightweight design. Overall, this vacuum flask is an excellent choice for those who are on-the-go and want to keep their drinks at the perfect temperature while also being able to mix in their favorite powders and supplements.