We do not stock the Q5521 filter. Email firstname.lastname@example.org
or call 1-888-801-7873 if you would like to special order the Q5521. An alternative option is the Q5621 filter below. This is a 12" version of the Q5521 filter which means it will last longer. The Q5621 has the same contaminant reduction as the Q5521. If you need a 10" filter, the Q5528 filter below is stocked and contains GAC, but does not reduce down to 10 microns like the Q5521. Both of these alternatives will fit in the filter head used by the Q5521.