Nogglers NG-011 2.25 Inch Hidden Passage is an excellent puzzle but a bit of care is in order here. On March 20, 2013, I posted a review on the Classic 3D Barrel hand crafted wooden puzzle and even talked about this puzzle being in the shape of a sphere. Now we have it in the shape of a cub. The “inside” or “hidden’ shapes of the 12 pieces are all the same for these three puzzles. This is not evident at first glance. The best way of describing this is to imagine this cube once assembled and then carved in the shape of a sphere or a barrel. Got It? This is often referred to as a “burr” puzzle and has been around for a long time and is popular and entertaining while at the same time challenging. Out of 10, I would give it a difficulty of 7 and is more suitable for a puzzler with some experience than a novice. I wrote a bit more in my review of the Barrel puzzle. These puzzles are made by many manufacturers in various qualities, prices and names. If you get stuck reassembling it, you can get some help from several excellent videos on YouTube. You can purchase this puzzle at Amazon.