2 Magnetic Vent Cover Sheets, 10"x12" - Block Cold Air Drafts - Cut To Any Size. MAGNETIC VENT COVER SHEET : Adhesive backing for decorating vent covers with photos or artwork. LIGHTWEIGHT : Lightweight so they stay in place on vertical walls. EASY Easy to apply and remove in just seconds. USE : Use to block unused vents to instantly improve air flow to other areas. SIZE : 10 x 12 peel off magnetic sheet, 20mm thin.