You are proficient with tower shields.
Prerequisites: Shield Proficiency.
Benefit: You can use a tower shield and suffer only the standard penalties.
Normal: A character who is using a shield with which he or she is not proficient takes the shield’s armour check penalty on attack rolls and on all Strength-based or Dexterity-based ability and skill checks.
Special: Fighters automatically have Tower Shield Proficiency as a bonus feat. They need not select it.
Source: Player’s Handbook (Page 101)