The Brunswick Defender Solid high-performance ball uses proven ball technology and advances it! The Portal X core is the previously used Prism core with a dense flip block added to the bottom. This addition adjusts the location of the mass and creates a higher RG and differential which increases the down-lane motion of the bowling ball. The ACT 3.0 Solid Reactive coverstock was engineered to make the mid-lane and backend hook more powerful. These two enhancements along with the attractive colors of this ball are sure to increase scores.