Doulton W9121200 7" Super Sterasyl Ceramic Filter Candle - Pack of 4 4 Replacement ceramic filters for gravity filter systems. Super Sterasyl outer ceramic shell, Activated carbon inside. Filters are self steralizing and re-cleanable. 7" in length. Includes rubber washer and wing nut. Fits Travel, Light, Big, Royal, Imperial, and Crown Berkey systems.