This thing contains a mounting plate and a drilling guide for the “Solarbotics L298 Compact Motor Driver”.
The base plate is 1.5 mm thick. M2 5 mm or 1/4″ 4-40 screws are needed to fasten the board to the mounting plate. The mounting holes are three mm in diameter.
The holes do not go through the lower layer to make it easier to print. You will have to drill them.