Combat Martial Arts

Prerequisite: Base attack bonus + 1.
  Benefit: With an unarmed strike, you deal lethal or nonlethal damage (your choice) equal to 1d4 + your Strength modifier. Your unarmed attacks count as armed, which means that opponents do not get attacks of opportunity when you attack them unarmed.
  You may make attacks of opportunity against opponents who provoke such attacks.
 
  Normal: Without this feat, a character deals only 1d3 points of nonlethal damage. Unarmed attacks normally provoke attacks of opportunity, and unarmed combatants cannot normally make attacks of opportunity.