There are eight dowel segments that you must fit into a box. You should be able to get seven pieces in with ease. What about the last piece?
I tested the puzzle on my two teenage children and both gave up after 5 minutes so I would say it's slightly challenging.
I understand the originator of this logic puzzle was Tesa Timonen of Sweden in 2002. I reversed engineered this version from online pictures.
More Info: https://www.instructables.com/id/Wood-Dowel-Puzzle/
Link to Amazon version: http://amzn.to/2hL9gHH