Introducing TRK 360 The Duo Soft TRK 360 version is here! World's Softest Golf Ball. Its velocity boosting core is engineered to deliver faster ball speeds and longer distances with the same great feel. The DUO Soft golf ball is a two-piece surlyn golf ball that delivers extreme distance, straight ball flight and an ultra-soft feel. The high-energy core delivers maximum distance off the tee, while the two-layer construction reduces spin on longer shots for the straightest ball flight.