wall26 Reflective Student Driver Magnetic Car Signs(Set of 3) Safety Caution Sign SET OF 3 - One For Each Side & the Rear - Reflective for added safety in low light or night time driving conditions. Size 12 x 3 x 0.1 inches Let Other Drivers know you are Learning to Drive with these bright eye catching Signs The text on these Student driver signs is easy to read block lettering great magnets for new learning drivers Easy to use and can be cut easily Made in USA Long Lasting Magnets For large projects that are in need of alot of strong flexible magnet material. Great for making custom Magnet Signs. Newer model cars increase its fuel efficiency by utilizing lightweight aluminummaterial rather than heavier metals for its car panels. This would result in the panels having little to no magnetic charge therefor rendering our magnets incapable of attaching to your car. We recommend testing the magnets on something that is metal first to rule out the magnet being defective. These metals can be found on your washing machine, refrigerator, oven, etc.<br> Similarly, if a simple screw or nut won&#039;t stick to the magnet, it is more than likely the same reason why magnets won&#039;t stay on an aluminum paneled car -- the screw itself doesn&#039;t hold a charge.<br> Other magnets will also not likely work with this magnet, because there may be a polarity issue [ N | S ] [ S | N ]. This causes the magnets to &#034;push away&#034; from each other rather than attract to each other. This can be most notableby children&#039;s magic tricks in making a magnet move without actually touching it.