Unscented Backflow Incense Cones When burned, smoke flows down the incense tower like a waterfall, creating an unusual and beautiful effect.These cones can only be used with backflow incense burners. Each tube contains 45 incense cones with instructions on how to use them safely.   Warning: Keep out of reach of children. Retroactive incense may damage varnished surfaces, always use on carpet. To be used indoors and without draughts for an optimal effect.