The toys are produced by the Kong Company of Colorado. The company founder, Joe Markham, invented the Kong in the 1970s, when he noticed his German shepherd Fritz damaging his teeth by chewing rocks. He found that Fritz enjoyed chewing on a hard rubber Volkswagen Bus suspension device, and spent about six years experimenting with different compounds to produce a chew toy of similar size and shape that he could sell to pet owners. Originally, Markham sold most of his products to Israel, Japan, Australia and the United Kingdom, but the Kong began gaining popularity in the United States in the mid-1980s, and have remained popular there ever since. The 2005 book Planet Dog describes the Kong as “possibly the best-known dog toy in the world”.