Generic, Text: Breakaway Boss:

The metal stud at the center of the reinforcing boss holds a compartment large enough to insert a single splash weapon, such as a vial of acid or alchemist’s fire, as a full-round action. On a successful shield bash attack, the weapon vial breaks and deals damage to the target as though it were directly hit by the splash weapon. The shield takes the normal amount of splash damage for being adjacent to the target, but no other creatures adjacent to the target take splash damage from this effect. A new splash weapon must be inserted into the breakaway boss for it to be used again.