Seals against air, dust and water. Most effective when mounted on exterior of outswinging door. Supplied with screws for easy installation. The CRL Triple Fin Vinyl Door Sweep is designed to prevent dust, moisture and wind from entering between the base of the door and the threshold. The triple fin design gives added protection against draughts and moisture. It is sized for a three-foot (0.9 meter) opening with an overall size of 36-1/2 inches (92.7 centimeters). Color: Dark Bronze Length: 36 in Installation Instructions 1. Measure, mark and trim door bottom sweep to full width of door. Trim seal to 1/16" longer than the trimmed housing (profile) on each end. 2. Close door and position door bottom sweep along outside bottom edge of door so that it makes light even contact with threshold. Mark door in center of slotted holes. 3. Drill pilot holes in door at marks. 4. Secure door bottom sweep to door with supplied screws. Adjust to ensure light even contact with threshold. NOTE: Not Recommended for inswing doors.