Available Bowie stud sizes:
S = Length 1 cm and 1mm square band width,
M = Length 1,5 cm and 1mm square band width
L = 2,7 cm and 1,5mm square band width
The earrings are made by hand, so it is possible that there are a few millimeters difference in the size. These differences are barely visible. The model is wearing a golden Bowie size S.