We do not stock the Q5421 filter. Email email@example.com
or call 1-888-801-7873 if you would like to special order the Q5421. An alternative option is the Q5621 filter below. This is a 12" version of the Q5421 filter which means it will last longer. The Q5621 has the same contaminant reduction as the Q5421. If you need an 8" filter, the Q5486 filter below is stocked and contains GAC and phosphate, but does not reduce down to 10 microns like the Q5421. Both of these alternatives will fit in the filter head used by the Q5421.