The garnet model for trucks sandblast？

The garnet model for trucks sandblast？
The garnet model used for sandblasts is: 10/20 20/40 30/60
Because the sandblating requirements of the trucks are generally low, 10/20 20/40 is generally used.
If it is an old trucks , the rust is relatively thick, generally 10/20. If it is a new trucks , it is for polishing, then 20/40 is used more