This gold testing kasoti is mainly used by jewelry professionals to determine actual gold quantity within the metal. It is used in combination with gold testing keys, and special gold testing acids (not included). This testing block comes with it’s own wooden storage case, with strong magnetic closure.* 6" X 3" X 3/8" * To Check Gold Percentage * Comes With Magetic Wooden Box * Eliminates Guesswork * Gives You Accurate Results