Factory Direct Filters Coupon Code: Get 5% OFF + FREE SHIPPING on Your Order at Factory Direct Prices at Factory Direct Filters. Coupon Code valid for limited period only. T and C: Must enter coupon code at checkout to apply 5% promotion offer. 10% discount is applied automatically when you upgrade to a 12 pack of air filters. Applies only to 1 and 2 inch filters. Not combinable with any other coupon code. Get Today’s Coupon Code, Promo Code, Promotion Code, Voucher Code, Special Discount Offers & Best Deals at CouponCodeOn.