A rare ring thought to have been produced by the Shinra Company, an influential utilities provider in another world. These valuable rings make their bearers more resilient, and thus are granted only to those who undertake especially perilous missions, such as 1st Class SOLDIERs.
Final Fantasy Brave Exvius description
Tough Ring(タフネスリング, Tafunesu Ringu?), also known as Touph Ring or Ring of Toughness, is a recurring accessory in the series, which first appeared in Final Fantasy VII.
Ring of Toughness is an accessory which provides DEF and SPR +30, and grants the passive ability Mettle: The equipped unit has a 20% chance to ignore fatal damage when its HP is above 80%, but it can be triggered only once during battle.