ROMPECABEZAS DE MADERA IQ TEST DOUBLE KNOT Fridolin IQ-Test Bamboo Puzzle, "Double Knot" This beautifully-made wooden IQ puzzle will challenge your problem solving skills. It may be easy to take apart, but can you put it back together? Smooth, burr-free edges and beautiful natural bamboo construction. Level four difficulty; "Unbelievable". Fridolin IQ-Puzzles are ranked Simple (1/5), Challenging (2/5), Dilemma (3/5), Unbelievable (4/5), Genius (5/5) Fridolin has been a manufacturer of quality toys and games since 1985