This is a rare piece of smart tennis equipment made in the USA. From somewhere the 1980’s that is, when you wanted to safe your expensive tennis balls from going bad after a few games. This “Tennis Ball Saver” is a hard plastic piece of power tool. With a few twists you create a high internal pressure to revive your balls or just keep them in good “Factory fresh” condition, ready for the next match. Instructions on the box that measures about the same size as a 3 ball tennis canister with a little bigger diameter of 8,5 cm or 3 1/4 inch. Great piece of vintage sports equipment still useful today if you rather play your balls then give them to your dog straight away. Do check out the blog post on Tennis retro style : Vintage Movie Stuff: Shia LaBeouf – Borg McEnroe.