I needed nets to prevent insects and birds from nesting in the inlets and outlets (3" PVC) of my water heater. It turned out to be the right ticket I don't know what the airflow reduction is, but it seems minimal.
Upgrade Your Stair Safety With SUSSEXHOME Polypropylene Carpet Strips - Easy To Install Runner Rugs W/ Double Adhesive Tape - Set Of 7 Decorative Mats In Brown
38 Review
IKSTAR EVA Thermal Plastic Door Cover 38" X 82": Insulated Magnetic Curtain Keeps Cool Summer, Warm Winter For AC Room, Kitchen & Stair - Brown
40 Review
Stylish & Safe: Sussexhome Carpet Stair Treads For Wooden Steps - 4-Pack Of Self-Adhesive, Pet & Kid-Friendly Indoor Treads To Prevent Slipping
51 Review
Ensure Safe Steps With Outdoor Non-Slip Stair Treads - 10 Pack Of 6"X40" Black Anti-Slip Strips
42 Review
Keep Drafts Out: 16Ft Long Silicone Seal Strip For Doors, Windows & Showers
33 Review
Keep Your Home Comfortable With 6.5Ft Of White Foam Insulation Tape For Doors, Windows, And AC - Soundproof, Dustproof, And Cooling
34 Review
White Self-Adhesive Tape For Weatherproofing Doors And Windows - 16Ft X 1.77In (45Mm) - Includes Weather Stripping And Silicone Seal Strip For Draft Stopping And Shower Glass Protection
27 Review
Universal Rubber Weatherstripping Kit For Garage Door Bottom Seals - Effective Replacement With Weatherproof Threshold Buffering & Sealing - 5/16" T Ends, 3 3/4" Width - 16 Ft Length
29 Review