Band of Eternity is a family of Scale of the Sands reputation reward rings which can be obtained from Soridormi only after solving the Quest:The Vials of Eternity.

Choice Introduction

I am pleased that you've decided to take up our cause. As a reward I will infuse a ring with the remnants of the Well of Eternity you brought me.

I offer you four different paths in which to unlock their power. Choose wisely, <name>. The sands of time flow easily in one direction and not the other.

After reaching exalted reputation there is a repeatable quest to swap rings for 75 0 0.