This is a filter for the Aroma Stream, a fine diffuser by means of air ventilation. You drip an essential oil on the filter, this can vary in drops, it depends on how big the room is and how intensely you want to smell the scent. It is good to know that you use 1 oil (single or blend) per filter, so not different oils one after the other. This is because then the scent no longer comes into its own and gets mixed up. It is possible to drip the same oil on the filter for a longer period of time. Once the filter is too full/saturated or if you notice that the scent is less pleasant, change the filter.