Doulton W9223022 Imperial UltraCarb OBE Ceramic Filter The Doulton Imperial W9223022 cartridge is open on both ends (OBE) and fits in standard 10-Inch filter housings The Doulton W9223022 UltraCarb Filter features a Sterasyl ceramic outer shell and activated carbon block which removes chlorine and organics W9223022cleanablefilter elements are designed to remove suspended solids, pathogenic bacteria, hydrogen sulphide, and lead