As one of its daily deals, Home Depot offers the Arm & Hammer Enhanced Allergen and Odor Control FPR 6 Air Filter 4-Pack in several sizes (20" x 25" pictured) for $19.99 with free shipping. That's tied with our mention from last month and the lowest price we could find by $14. They last for up to 90 days and help reduce common household and pet odors. Deal ends today.