Muyu Stone has the quality to gradually mineralize and pH balance your drink while a mix of immediately activated ionished trace minerals join the drink and reach each (water) molecule in a profound way. The Mug is made of the original Muyu Stone material from Taishan (Mount Tai). Its from Marine deposits of 580 million years ago, full of health sustaining trace minerals and is beneficial to the body's health. Once you drink with a Muyu Mug and feel the difference of the added trace minerals, you will always choose it as your favorite. All Mugs are delivered with lid. You are just one step away from having one yourself.