Magnetic fireplace vent covers are the most common kind of airtight vent covers. They're simply magnetic sheets that fit over your normal vent covers. This type of magnetic cover has been used on small floor vents to redirect air flow of heaters for years. Our larger magnet is perfect for fireplace vents that leak cold drafty air in the winter and warm humid air in the summer. As an added benefit, magnetic fireplace vent covers help to keep stink bugs, spiders and other insects out of your home. Our high quality fireplace vent covers have a thickness of 0.030".When the black magnetic vent cover is on your black vent you will not even notice it! NOTICE; our cover is shown in gold so you can see the placement of the cover on the black fireplace.. If your fireplace vent area is a bit smaller than the cut size, the length is easily trimmed with scissors or a cutting wheel for a perfect fit. Draft Decor's vent cover can be easily removed when you use your fireplace. Stick it on the side of your refrigerator to keep the magnet smooth. It wipes clean with a damp cloth and will last for years. See photos to view installation photos and how to measure. Easy, functional and will help you be more energy efficient! Save energy and make rooms more comfortable, reduce your fuel bills.