From my review of Wild Berry's Fizzy Pop incense powder.
Oh, I see. It's a traditional Chinese method of burning incense. If you search "incense seal" on aliexpress, you can find censers, tools, and ash for it. You can buy incense powder, make your own, or just burn plain aromatic wood powders. It's a really nice, clean method of burning incense when done properly using good material. It's also great for testing formulas if you make your own incense sticks.