These brushes are designed to clean both pellet stoves vents and dryer vents. On one side of the card is information about using them to clean pellet stove vents and the other side is about using them to clean out dryer vents. The brushes are designed to navigate a sharp turning radius without getting caught in elbows. Brush filament is 0.020-Inch poly. Feature . Pellet stove brush. Made with quality nylon bristles. Heavy duty ball tip guides brushes through narrow offsets and bends. least aggressive pellet vent brush. 0.25-20 thread. Size - 3 in.