Here is a tennis ball you can't miss - our 6" round tennis ball car magnet. Purchase our Magnetic Tennis Ball Car Magnets, or we can make Custom Tennis Ball Car Magnets for your team or school too. This 6” magnetic Tennis Ball is manufactured and printed in the USA. We print on premium quality, super-thick (.030) magnetic material with top quality, UV protected inks. Be sure to remove, clean and reposition your magnet once a week or so.