From Pathfinder #202: Severed at the Root, which isn't enabled.

Nail Bomb (Lesser)

ITEM 2

UNCOMMON ALCHEMICAL BOMB CONSUMABLE SPLASH

Price 8 gp

Usage held in 1 hand

Bulk L

Category martial

Group bomb

Damage 2d4 piercing + 1 splash

Range 20 ft.

Activate Strike

This pressurized iron casing bursts open when struck, releasing cold iron shrapnel. The bomb deals 2d4 piercing damage and 1 piercing splash damage from a cold iron source.

Pathfinder #202: Severed at the RootORC