Model Compatibility: Compatible with eufy Robot Vacuum Omni S2. Suggested Replacement Frequency: We recommend replacing every 3 months, depending on your usage frequency. S2 sprays fragrance as it cleans to leave your whole home smelling like new. Tool-Free Installation: Open the robot's magnetic top cover, remove the protective sticker from the fragrance, and place it inside the machine. Number of Fragrances: Contains three Citrus & Basil scented fragrances. Genuine eufy Accessory: For optimal performance and to extend the lifespan of your vacuum, always use genuine eufy accessories.