In short, the US Department of Transportation (USDOT) is going to require that you have your Company Name and the US DOT number installed on the power train of your vehicle with a minimum of 50 feet visibility. US DOT numbers that are 2” tall or larger are visible to someone who has 20/20 vision or corrected vision. All of the US DOT stickers and magnetic signs that you can purchase at DotNumberStore.com will be US DOT compliant.