The Transducer is created to hold two different size cartridges for two different purposes: The Moodshot & Houseblend. The smaller size is the moodshot, and the bigger size is the House blend.The moodshot is the quick and interchangeable cartridge that you can use to complement your +3 hour needs during the day.When falling in love with one specific fragrance, the House blend (30ml cartridge) will enable you to scent your home with one specific blend for a duration of 1 to 2 months.Please note that once you have a House Blend in your diffuser and you want to create a momentum for yourself with a Moodshot, the Transducer will diffuse the small cartridge withholding the moodshot.