Back Flow Incense Cones Tub £2.99 Quantity: at £2.99 each 2 in stock. Backflow Incense Cones when they are burned, the smoke flows down the incense tower like a waterfall, creating an unusual and beautiful effect. These cones are only for use with Backflow Incense Burners. Each tub contains approximately 45 assorted Incense cones with instruction how to use safely. Warning: Keep away from children. Backflow Incense can damage varnished surfaces, always use on a mat. To be used indoor and with no drafts for best effects.