Doulton W9121715/W9121709 10" Super Sterasyl Ceramic Filter Candle-Pack of 2 2 Replacement ceramic filters W9121715/W9121709 for gravity filter systems. Fits Royal, Imperial, and Crown Berkey systems. Will NOT fit Big Berkey. Includes rubber washer and wing nut. 2" wide by 10" tall. Threaded stem: 1 1/4" long. Super Sterasyl outer ceramic shell, Activated carbon inside. Filters are self sterilizing and re-cleanable.