Our Lizzard double-walled stainless steel Protein Shaker flask has been designed to be portable, durable and fashionable. It is made of 18/8 stainless steel – the highest quality steel used for food preparation, giving the flask lifetime durability and eliminating the need for plastic and glass, making it the ultimate eco-friendly liquid bottle. The double-wall has been developed to keep hot drinks warm for up to 8 hours and cold drinks cool for up to 18 hours.