A challenging & beautiful box of our own design. It reminded us of the southwestern US Adobe Pueblo dwellings built into caves, thus the name. You must align the 5 side arms to the correct position for the cover to allow the cover to slide off. The arms slide left and right. Each arm has 10 possible positions so the number of possible combinations of positions is quite large (10 x 9 x 8 x 7 x 6 = 30,240). We have found that a typical solution time is 30 to 40 minutes. Occasionally done faster, but more often than not people give up and look at the solution which we provide. The box we make from an attractive 1/4" thick floorboard material and the arms are wood. The sides and bottom are all jointed which gives both a super solid construction and a nice visual image. Inside, we have felt line the bottom of the box. Measures about 5.5" x 3.5" x 3.2" high on the outside.