Outdoor safe custom shape magnet. 2 to 3 square inches. 30 mil thick. Custom magnet is unique and we are here to make your magnet as unique as your idea. TuffMag (TM) magnet is 30 mil thickness and will work on cars or any other metal surfaces are perfect for outdoor applications - water repellent, fade resistant and outdoor safe. Write-on/Wipe-off surface not available.