They are basically a scented candle, but different! They are pieces of scented wax without a wick, that are melted instead of burned. By melting instead of burning them, the oils are vaporated into the air, fragrancing your room, without burning the oils and burning the wax.
How to use them?
Rapeseed wax's melting point is higher than other waxes like soy and beeswax. It's therefore important that you use a small oil burner so the maximum distance between the cup and the tealight is 5cm. If your oil burner is bigger or higher, just place the tealight on something to bring the flame closer to the cup.