They carry something similar to AllerTech Vent Guard Filtration Kits for 4X12 floor registers: sku 670128 "4 in. x 12 in. Vent Filters (12-Pack)" They also carry a cut to fit filter that you could tape to a register like the AllerTech filter: sku 778990 "24 in. x 36 in. x 1 in. Permaire Pad Air Filter" They aren't available at all stores, you should check online for inventory in stock before going.
I believe they do.
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