Greater Two-Weapon Fighting [General]
Prerequisites: Dex 19, Improved Two-Weapon Fighting, Two-Weapon Fighting, base attack bonus +11.
Benefit: You get a third attack with your off-hand weapon, albeit at a -10 penalty.
Special: A fighter may select Greater Two-Weapon Fighting as one of his fighter bonus feats.
An 11th-level ranger who has chosen the two-weapon combat style is treated as having Greater Two-Weapon Fighting, even if he does not have the prerequisites for it, but only when he is wearing light or no armor.
Source: SRD 3.5 Feats