Wilson Staff Zip Golf Balls (1 Dozen) Behind the patent-pending zero compression core is a high-velocity Neodymium catalyzed polybutadiene Patented HPF mantle layer encases the zero compression core with a speed-generating mantle for distance and higher iron spin rates Super-soft ionomer cover grabs the club face for higher spin and amazingly soft feel. Unique flat-bottomed, shallow dimples rip through the air to create a more stable, penetrating flight. It's the perfect option for players seeking soft feel, great distance and greenside control.