The wood blade is removed from the holder. The blade is solid (the illustration shows the blade fully inserted into the frame, with the hole through it). The volunteer places his finger through the hole in the frame. The blade is positioned at the top of the frame, then- BAM! The blade is pushed right through the finger, without hurting it a bit.
But wait! THAT'S NOT ALL! The frame is opened to reveal that the finger is now through the hole in the formerly solid blade! How in the world is that possible???
Supplied ready to work, with instructions. Chopper is precision made of wood. About 4" high.