Callaway Warbird 21 Yellow Golf Balls The Warbird 21 Yellow Golf Balls by Callaway are designed to provide maximum speed and maximum distance. Callaway has used a high energy core to achieve this. You also get an amazing feel and pleasing sound with these Golf Balls. Maximum Distance Callaway uses a high-energy core to unlock more distance at any swing speed. Excellent Feel and Control Featuring an ionomer cover as well as a large core, this Golf Ball provides a great feel as well as excellent greenside control. High Launch Callaway has used HEX Aerodynamics to reduces drag, promoting a higher launch for more speed and distance.