Ich zitiere hier mal die entsprechenden Feats (und deren Prerequisites/Improvements)
Brawl
Benefit: When making an unarmed attack, the character receives a +1 competence bonus on attack rolls, and the character deals nonlethal damage equal to 1d6 + his or her Strength modifier.
Normal: Unarmed attacks normally deal nonlethal damage equal to 1d3 + Strength modifier.
Improved Brawl
Prerequisites: Brawl, base attack bonus +3.
Benefit: When making an unarmed attack, the character receives a +2 competence bonus on his or her attack roll, and the character deals nonlethal damage equal to 1d8 + the character's Strength modifier.
Normal: Unarmed attacks normally deal nonlethal damage equal to 1d3 + Strength modifier.
Knockout Punch
Prerequisites: Brawl, base attack bonus +3.
Benefit: When making the character's first unarmed attack against a flat-footed opponent, treat a successful attack as a critical hit. This damage is nonlethal damage.
Special: Even if the character has the ability to treat unarmed damage as lethal damage, the damage from a knockout punch is always nonlethal.
Improved Knockout Punch
Prerequisites: Brawl, Knockout Punch, base attack bonus +6.
Benefit: When making the character's first unarmed attack against a flat-footed opponent, treat a successful attack as a critical hit. This critical hit deals triple damage. The damage is nonlethal damage.
Special: Even if the character has the ability to treat unarmed damage as lethal damage, the damage from a knockout punch is always nonlethal.
Ich schaetze mal dass es diese Feats gibt liegt an der
Nonlethal Damage Problematik in d20 Modern