Tuffy Zoo Hippo Dog Toy. Great for interactive play with one or multiple dogs. Best for dogs who like to whip their toys and play tug for hours. Floats in water, and its machine washable, (air dry). 4 LAYERS OF MATERIAL. Tuffy Ultimate toys are made with UP TO 4 layers. 1 layer soft fleece on the outside. 1 to 2 layers of industrial grade luggage material on the inside. 1 layer of plastic coating on the inside.