An important part of the air purification system, a UV bulb destroys germs and bacteria | UV reduces the growth of odour-causing microbes on the surface of the air purifier filter | Microscopic airborne organisms get trapped in air filters, which could multiply if left untreated | When bacteria/viruses are exposed to wavelengths of UV light, they become incapable of reproducing | Indicator light on the air purifier glows red when it's time to replace the bulb | Compatible with TruSens Z3000 Air Purifier and TruSens Z3500 Air Purifier