How they work. The stick holder's block holds the stick at 15° over the tray, so the ash falls where it should; the holes take the usual 3 mm bamboo sticks (one, or three at once), and there's a shallow dish at the bow for a cone. The backflow burner needs backflow cones — the kind with a hole up the middle — sitting in the dish on top; their smoke is heavier than air, sinks through the column into the chamber, and pours out of the slot down the steps. Both print in one piece. Incense burns at its tip, in the air, and only ash ever touches the plastic — but keep the burning end in the tray and never rest it on the body. Not for charcoal or resin burners.