The graphics in this sign were based on a photograph from a storm chaser Craig Maire who was the Greensburg Kansas tornado on May 4th 2007. It was after dark but the lightning lit up the EF5 twister for the photo. This was the first EF5 tornado I believe since it was the first season using the new EF rating. I was in Woodward, OK at the time so I missed it. Certainly an interesting but devastating day in south central Kansas! This magnetic sign is small enough to keep in your vehicle and can quickly be installed at a moments notice. If properly cared for this sign will give you many years of service. It is produced with the same materials as most industrial grade signage. Our signs are digitally printed on 3M high performance vinyl and covered with a clear over-laminate. They are designed for metal vehicles only (except aluminum). These are not sold in pairs so if you want two you will need to order 2 etc. This sign measures 12 inches across by 7 inches tall (30 x 17.5 cm) and should fit almost anywhere on your vehicle.