This design is a parametric handle for doors or furniture with embedded handle. Sometime there is space and the design can be impractical...
The meaning of most parameters is expressed in the cross section schema included in the images.
For the other parameters here are there meanings:
Hight=48; // hight of the handle
Diameter_1=4; // diameter of the screws
Diameter_2=7.5; // Diameter of the screw heads
Screw_length=20; // Lenght of the srews
Screw_distance=24; // Distance between the two screws
Nut_thikness=3; // Thikness of the nut
Nut_size=7; // dimention of the nut, ie distance between two oposite sides of the hexagon

This model uses two screws and two nuts. By default i use M4 X 20mm but this can be modified.

For detailed explanations on how to use a customizable part look here: https://www.instructables.com/Learn-How-to-Use-Customizable-3D-Models-With-OpenS/