The Doulton W9331001 requires the following:
The Doulton Counter Top Ceramic Water Filter- W9331001 is designed for use as a countertop filter and is connected to the mixer tap via a diverter valve. The Doulton ceramic filter should be fitted with any 10" long x 2" diameter Doulton short mount filter candle (not included). This counter top filter has a typical output of 300 liters per hour and has 3/8" push fit connections.
Doulton Counter Top Ceramic Water Filter- W9331001 specifications: