I have had a lot of trouble with first layers of my prints being good, only to find that the second is then too low, resulting in a really scratched up print. These two models helped me with z-offset and some flow calibration. The 0.2 mm one is, you guessed it, a 0.2 mm layer height, and the other one is a 0.3 mm first layer.
The author marked this model as their own original creation.