Based on one of the standard Meanwell 1-Inch by 2-Inch 60W isolated power bricks, this PCB takes an 18-75V input and converts it into +/-12V voltage rails at 30W each. For this board there is no real care for the specifications of the brick itself, but what does matter is that it's simple and can be switched out easily to accommodate other voltage output levels. The filters are a combination of datasheet recommendations and other common parts.