Backflow incense burner large pebbles into pool backflow incense burner is specially designed to create smoke that cascades downwards, pouring dramatically down the tower with a stunning effect. once you have lit your incense cone, it will begin to smoke, the incense is heavier than air and it will fall dramatically in swirls and twists, through the hole and down over the item, to pool at the bottom. it is incredible to watch and very relaxing.