LUX Mundi Thread Adapter
The 24 means the number of threads per inch. 10 is the diameter and 24 threads(pitch) per inch (TPI).
What Is TPI?
Pitch is the axial distance between adjacent repeating features on a mechanical element. TPI is an imperial unit of measurement for pitch, commonly used in the United States. As its name suggests, it is the number of times in which the feature appears over a linear distance of 1″ (25.4 mm)