The lightsaber is the name of a fictional weapon that plays a key role in the movies, games and novels that constitute the Star Wars universe. Lightsabers are science fiction versions of their namesake, the saber, but with the metal blade replaced by something resembling a solid bar or cylindrical beam of plasma about one meter long. Lightsabers differ in color (red, blue, green and purple have appeared in the six films, and other colors appear in the Expanded Universe) based upon the specific crystal used in construction. Though they often behave like regular swords, they have been depicted as able to penetrate and cut through most matter with little or no resistance (due to their energy-based nature), and to deflect shots from blasters, the ranged weapons used in the Star Wars franchise. Obi-Wan Kenobi described them as "an elegant weapon for a more civilized age."