This is short and sweet, and exactly what the title says: three new simian races for a Pathfinder RPG campaign. It has the warrior-like Mangani, the shapechanging Shift, and ends with the Chinese-legend-inspired Wukong. There are enough differences between the three to make them distinct, and the PDF includes a pair of feats that can eb taken by any character who has a natural climb speed and/or a prehensile tail.
It is very, very worth the cost of buying it. Especially if you're looking for something new for the game table.