Sacred sticks for offering to the havan, or the sacred fire. These sticks are offered to the fire by chanting shlokas which invariably end with a 'swahaa'.
Fire or agni is one of the five manifestations of life. In ceremonies like Wedding, birth, festivals etc., the fire is lit symbolizing the presence of God and Havan samidha sticks are used in Havan.
Havan is a sacred fire ritual that accepts our offerings and sacrifice. The sacred fire acts as a link between man's consciousness and the cosmic consciousness. The fire also has the ability to convert the physical components (offerings that symbolize the sacrifice into the fire) into the psychic components as offering to the deities presiding over the Havan.