Sulfur vapor is known to penetrate through silicone and other organic passivation. SSM’s RG series uses inorganic passivation which is almost equivalent to a hermetic seal. Sulfur is also known to react with silver and sometimes with copper to create metal sulfides that causes resistors to drift or to become open in extreme cases. Susumu’s RG series does not contain any silver or copper; hence there is no reaction with sulfur.