can only be glued to steel registers. Our vent covers can only be used in steel exhaust ports.Cannot be used in exhaust ports made of aluminum, plastic or wood.Magnetic ceiling vent covers can be tightly attached to floor, ceiling and wall vents without worrying about falling. The household vent cap is made of strong anisotropic rubber magnets with a white PVC that provides excellent magnetic flux and 100% protection.The magnetic register vent cover has stronger fixing strength! The household ceiling magnet vent cover measures 5.5 inches x 12 inches (approximately 14.9 cm x 30.5 cm), fits most standard air registers and is easy to cut, supporting cut sizes to fit your special size exhaust ports. This vent cover closes the registers of unused spaces in your home and reduces the heating and air conditioning costs associated with controlling these space temperatures.Save energy and save money! Register cover prevents unnecessary passage through the vents and reduces noise transmission through the vents.It also prevents small things and other harmful substances from passing through the pipes, creating a comfortable home environment. Color:As Shown Material:Rubber Iron Package Contents: 2 * magnetic vent cover Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.