Overview & background
A reed diffuser is a flame-free way to scent a room: rattan reeds stand in a bottle of fragrance oil, draw the oil up through their porous structure and release it into the air. The bottle needs a narrow neck so only a few reeds are exposed at once (controlling the throw), and a heavy base so a top-heavy bottle full of reeds does not tip.
Because there is no flame, the format is popular where candles are unsuitable, and the bottle stays on display for weeks, so its appearance matters as much as its function.
