Vaportek Cartridge - Neutral Scent Fits Restorator and Optimum 4000. Good for 270 hours usage. AR48A - Vaportek Cartridge - Neutral Scent AR48B - Vaportek Cartridge - Berry Scent AR48C - Vaportek Cartridge - Lemon Scent AR48D - Vaportek Cartridge - Orchard Scent AR48E - Vaportek Cartridge - Forest Scent AR48F - Vaportek Cartridge - Cinnamon Scent AR48G - Vaportek Cartridge - Lavender Scent