Groove Tube – Orange Level is an intriguing brainteaser. It is like nothing I’ve ever come across. It consists of a black tube about 4 1/2 inches long and about 1 inch in diameter. At about the center of this tube there is a small “knob”. The colored sleeve has a maze on its inside and not visible. The object is to maneuver the sleeve so that the “knob” finds its way through the maze, thus releasing the sleeve from the tube. There seems to be no logical way to solve this brainteaser because the maze is not visible. So, trial and error seems to be the only was to get the sleeve off. In spite of the challenge, it is not intimidating and just about anyone, regardless of age wants “to give it a try”. It is a great puzzle to carry around and “fiddle” with on a plane, bus or whatever. It does not require one to look at it while trying to solve. I have spent quite a bit of time on it, without success but I fully expect it to pop off when least expecting it. It is very well made of sturdy plastic and there are no parts to get lost. The only precaution I would like to make is that it might be possible for someone to “strip” the maze or “knob” if some macho type were to twist it with excessive force. However, with normal handling it will last for a very long time. Once you solve it, all you have to do is simply put the sleeve back, make a few twists and turns and it’s ready to be solved again. There are 6 versions of this puzzle, Yellow, Orange, Green, Blue, Red, and Black and they vary in difficulty. One of these days, I’m going to get the sleeve off and when I do, I return to this review to boast about my accomplishment. You can purchase this puzzle at Amazon.