Though they are technically sling ammunition, these thread- or cloth-wrapped pebbles are mainly used for signaling or celebration rather than battle, as they barely hit hard enough to sting. When soaked in oil or strong alcohol, they burn brightly for 1 round, illuminating an area like a candle and creating brief streaks of light as they fly through the air. They generally aren’t hot enough and burn out too quickly to ignite combustibles.
Pathfinder Player Companion: Halflings of Golarion. Copyright 2010, Paizo Publishing, LLC; Authors: Hal MacLean and Amber E. Scott.