The S is a size A and fits someone whose height is up to 5'4" with a hip size up to 100 cms at the extreme.
The M is a size B and fits someone whose height is up to 5'9" with a hip size up to 110 cms at the extreme.
The L is a size C and fits someone whose height is up to 5'10" with a hip size up to 120 cms at the extreme.