From the Artist, Keith Brown: "This bottle contains a safety pin through a hole in a 16 penny nail which is passed through 12 7/16" x 3/8" pieces of wood, The safety pin is also attached at bottom of bottle. Placing the wood pieces and passing the nail through all 12 pieces was the easy part; securing the safety pin through a hole in the nail past all of the pieces was the ‘thrilling’ part. This was simply a test to see if I could do it." The bottle opening is 7/16 inches.