One filter lasts up to 60 days. Unique 5 step process, reduces pesticides, heavy metals, chlorine and limescale. Designed to fit Aqua Optima Filter Jugs, Russell Hobbs, Kettles & Chillers and Morphy Richards, Cookworks, La Cafetiere and Sabichi water filter kettles. Twin pack lasts approximately 4 months. Manufacturer's 5 year guarantee.