"The Piston Box puzzle is also known as Internal Combustion or Pandora's Box. This is a hefty metal puzzle for its size, and is composed of 4 burr pieces and a frame. From previous listings, "it was invented by Tadao Muroi and designed by Marcel Gillen." Assemblies that require different numbers of steps are possible. A review describing this can be found here: http://smallpuzzlecollection.blogspot.com/2011/07/internal-combustion.html"