Extend the core to between approximately halfway along the protective pipe and its tip. Keep the core tip inside the protective pipe rather than extending it beyond the pipe. Draw individual strokes where you want to add brow hairs. For smooth application, hold the tip of the protective pipe perpendicular to the skin.
If the core extends too far, retract it to adjust. Avoid strong impacts or dropping the pencil, as this may break the core or stop it from retracting. Gently wipe the protective pipe if it becomes dirty, and close the cap securely after use.