The idea of the character of John Rambo carrying a survival knife was not in David Morrell's original 1981 novel. It was actually first suggested by knife enthusiast Sylvester Stallone because it would not only have something to go along with the character, but also because it would illustrate his creative guerrilla training. The official replicas on the market have several differences with the knives used in the movies, both in materials and little details.