Storm continues to evolve the game of bowling. This time they are doing so with the Storm Gravity Evolve high performance bowling ball. The Gravity Evolve uses the Shape-Lock High Density (HD) core that has been used in previous Gravity balls. This HD core has a lower RG and higher differential which creates more flare potential. The proven SPEC coverstock sticks to the lane creating a heavy roll and is great for controlling the midlane.