Shield Specialization( Player's Handbook II, p. 82)
[Fighter Bonus Feat, General]
You are skilled in using a shield, allowing you to gain greater defensive BENEFITS: from it.
Proficiency with shields,
Choose one type of shield from the following list: buckler, heavy, or light. When using a shield of the appropriate type, you increase its shield bonus to AC by 1.
You can take this feat more than once. Each time you select it, choose a different type of shield. A fighter can select Shield Specialization as one of his fighter bonus feats