SHIELD SPECIALIZATION
Type: Combat, Tier 2.
Prerequisite: Proficiency (Light Armor), Shield Focus.
Benefit: While using a shield that benefits from the Shield Focus feat, you gain DR/magic equal to half the shield's shield bonus (including enhancements). If you already have DR/magic from another source of equal or greater amount, you gain DR/adamantine instead.

IMPROVED SHIELD SPECIALIZATION
Type: Combat, Tier 3.
Prerequisite: Proficiency (Light Armor), Shield Focus, Shield Specialization.
Benefit: While using a shield that benefits from the Shield Focus feat, you gain DR/adamantine equal to half the DR you get from Shield Specialization. If you already have DR/adamantine from Shield Specialization, this becomes DR/- instead.

GREATER SHIELD SPECIALIZATION
Type: Combat, Tier 4.
Prerequisite: Proficiency (Light Armor), Shield Focus, Shield Specialization, Improved Shield Specialization.
Benefit: The DR you get from Shield Specialization increases to the full shield bonus instead of half. Consequently, this increases the DR you get from Improved Shield Specialization as well.