Good used condition, no instructions (I am sure as a collector you will know how it works).. Not sure it is the exact name MW used for this effect.
ix solid blocks of various colors are passed for examination and two colors selected by a spectator. All blocks are returned to a handsome, brass trimmed chest and rigidly secured by a metal skewer. The chest is closed and inverted. When the lid is opened, the selected blocks fall freely to the table while the remaining blocks remain locked firmly in place.
The longe needle / spike would benefit from polishing.
