Sausage Dog 18/8 stainless steel, insular bottle. Sold with cocooncap. TM ecococoon bottles are completely unique. They have toiled long and hard to develop a cap that won't leak without using straws or sippers and a bottle that won't get slippery with condensation. The double walled design not only makes these bottles sturdy, but also insulates the liquid so cold drinks stay cold and hot drinks stay hot, just they way you want them! Constructed out of 18/8 stainless steel, these bottles are built to last.