Replacement filter for Grenoble series to bring your 4-in-1 humidifier/air purifier back on track. It's easy and simple to replace your old, worn out filter from your Klarstein device and return its performance level to an optimal state. Like the original, the replacement filter is antibacterial and it eliminates bacteria, dust and mold spores from the air and thus provides a significantly improved atmosphere in work and living spaces.