1st day fresh for 100 days (50 days each, on low). Scratch and sniff. Formulated with: No dyes, no phthalates, no formaldehyde. Low level indicator blue light flashes when it might be time to refill. Febreze Warmer has a Blue Light That: Flashes twice when first plugged in to show it's working. Flashes continuously when it may be time for a new refill.