Quantities are EXTREMELY LIMITED!!!The Thunder Zone combines a highly successful coverstock called PK Traction 6 and a proven Ultra Low RG Asymmetric core to create a high hooking ball with strong continuous backend. The secret is in the PK Traction coverstock. The PK Traction coverstock passes easily through the heads, then responds quickly in the mid lane and continues its strong motion through the backend into the pins that is sure to make a Thunderous explosion.Product Type Bowling Balls