Made of natural, eco-friendly materials Buckwheat inside makes irresistible crinkle sound Contains premium KONG North American catnipThe KONG Naturals Crinkle Rings are specifically designed to appeal to your cats natural hunting instincts. The crinkle sound instantly sparks curiosity and the combination of natural fabric and catnip provide exercise and entertainment. These toys are designed to appeal to the natural stalking and hunting instincts of the indoor cat. KONG Naturals are ecologically responsible cat toys. The materials and dyes used come from natural, renewable resources.