A vacuum flask water bottle has a capacity of 500ml and a double-walled construction that keeps liquids hot or cold for extended periods. The stainless steel construction is durable and long-lasting, and the bottle is easy to clean and resistant to corrosion. This type of water bottle is an environmentally friendly and cost-effective way to keep liquids at the desired temperature while on the go. When selecting a bottle, consider the insulation properties and any additional features, such as a non-slip grip, to ensure it meets your needs.