These Notched Sticks are a 2x2x2 Burr puzzle, the origin of which is quite old. This particular design pattern is sometimes called the "Grandfather Burr". Unless you are very familiar with burrs, you will find it quite challenging.
Burr puzzles can have hundreds of internal cuts and still "notch" together to form the X-Y-Z axis shape that you see in the picture. This Burr will come apart relatively easily, but oh my getting the pieces back together is quite another story. The size is quite good, large enough to be a substantial puzzle, but small enough to easily handle the pieces. Each piece measures about 3" long x 1"square.
Level of Difficulty: Level 3