Challenge your brain and eyes The unique design of the QiYi DNA Concave 3x3 Rubik's Cube is a challenging and engaging puzzle that will test your brain and eyes. This cube is made of high quality materials and has a unique design that creates an optical illusion. Why is it worth buying? A challenging and engaging puzzle Unique design, creates an optical illusion Made of high quality materials Will last for many years A great gift for anyone who loves puzzles Measurement: 5.7 x 5.7 cm This cube is a great choice for those looking for a challenging and engaging puzzle that is also beautiful. It is made of high quality plastic and has a unique design that creates an optical illusion. Solving a cube requires a lot of effort and patience, so it's a great way to improve your concentration and problem-solving skills.