The King Stone (キングストーン Kingu Sutōn) is Kamen Rider Black and Shadow Moon's means of transformation. Embedded upon the center of their belts is the artifacts known respectively as the Stone of the Sun (太陽の石 Taiyō no Seki) and the Stone of the Moon (月の石 Tsuki no Seki). Since both existing King Stone had same functions, it also gave the bearer the equal ability as the second bearer (e.g. control over Battle Hopper, summoning weapons like the Satan Sabre).