From D&D Wiki
|This material is published under the OGL|
Sap Adept (Combat)
You know just where to hit to knock the sense out of your foe.
Prerequisite: Sneak attack +1d6.
Benefit: Whenever you use a bludgeoning weapon to deal nonlethal sneak attack damage, you gain a bonus on your damage roll equal to the number of sneak attack damage dice you rolled.