Complete shrinkage and loss of function of the testis.
For a 20% rating, medical records and physical or imaging findings need to show complete atrophy affecting both testes. A VA or private examination documenting bilateral complete testicular atrophy is central to establishing this level. For a 0% rating, the same type of exam findings would show complete atrophy limited to one testis. Because special monthly compensation for loss of a creative organ may also be available, records or exam findings that confirm the nature and extent of the atrophy on each side are important. Statements from you describing how the condition affects your daily life can also be part of the record, though the rating itself turns on which testes are affected and whether the atrophy is complete.
Conditions that are often caused or made worse by this one. If you have any of these, they may be claimable as secondary service connection.