We do not stock the Q5421-P filter. Email firstname.lastname@example.org
or call 1-888-801-7873 if you would like to special order the Q5421-P. An alternative option is the Q5621-P filter below. This is a 12" version of the Q5421-P filter which means it will last longer. The Q5621-P has the same contaminant reduction as the Q5421-P. 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-P. Both of these alternatives will fit in the filter head used by the Q5421-P.