Wilson tennis balls, which are used at the US Open, weigh exactly 58.27 grams. That’s the same weight as a size M chicken’s egg. It’s not exactly essential knowledge. But it’s a handy fact to bear in mind when, at the end of August, the world’s best players compete once again for victory in the fourth and final Grand Slam tournament of the year on the hard courts of the USTA Billie Jean King National Tennis Centre in New York. To get into the spirit of things in advance, why not hit a few balls yourself? We’ve got the perfect outfit for you.