Your ability to see in the dark is greater than normal.
Prerequisite: Darkvision.
Benefit: The range of the character’s darkvision doubles. This feat does not stack with darkvision granted by magic items or nonpermanent magical effects.
Special: This feat may be taken multiple times. Its effects stack. Remember that two doublings equals a tripling, and so on.
Source: Standard Reference Document under Open Game License v1.0a, which updated this feat originally published in the Epic Level Handbook, page 58.