The Ervan Flask is a great choice for a lightweight insulated water bottle. It is made from high quality stainless steel and is designed to keep beverages cold for up to 24 hours and hot for up to 12 hours. 

The bottle is double walled and vacuum sealed for maximum insulation, and it comes with a leak-proof lid that is easy to open and close. The Ervan Flask is also lightweight, weighing only 9.6 ounces, and it is slim and compact enough to fit easily into a bag or backpack. It is also BPA free and dishwasher safe, making it easy to clean and care for. 

The Ervan Flask is a great choice for anyone looking for an insulated water bottle that is lightweight, durable, and leak-proof.