This bowling ball ships PRE-DRILLED. There are 5 sizes and the sizes that we drill are based on the weight of the ball. X-Small: 6lbs- Ages 8 and under, Small: 8lbs and 9lbs- Ages 8-11 and womens ring size from 8-11, Medium: 10lbs, 11lbs, and 12lbs, Ages 11-15 and Adult Ring size 10 or lower, Large: 13lbs and 14lbs, Mens ring size 10-12 or people with larger hands, X-Large: 15lbs and 16lbs, Mens ring size over 13 or people with extremely large hands. If you would like a different size drilled for the weight you selected, you must contact us via email as soon as your order is placed with your order number. Pre-Drilled bowling balls cannot be returned or exchanged. The Hammer line gets more attitude with the new Anger! The HK22 coverstock has changed how we develop bowling balls and created endless performance possibilities. We can explore a broader range of core numbers because of HK22 s versatility and strength. Even when shiny, its stronger characteristics in oil allow us to get more out of higher RG core designs than ever before and opens up a new realm of reaction. The Anger s length and skid-flip motion are unmatched in the Hammer line-up. We started with a modified version of the Infamous core, a dynamic core with a high RG and designed for length. Adding HK22 with CT Reactive Flip additives makes this the most responsive Hammer ball on medium to lighter conditions. PERFORMANCE: Mid COLOR: Black / Red / Caramel CORE: Modified Infamous COVERSTOCK: HK22 - CT Reactive Flip COVER TYPE: Pearl Reactive FINISH: 500, 1000, 1500 Siaair / Factory Compound WEIGHTS: 16-12 Pounds LANE CONDITION: Light to medium oil REACTION: Length with strong backend WARRANTY: Two years from purchase date 16 lbs - RG (2.572) DIFF (0.041) 15 lbs - RG (2.567) DIFF (0.049) 14 lbs - RG (2.603) DIFF (0.049) 13 lbs - RG (2.585) DIFF (0.040) 12 lbs - RG (2.608) DIFF (0.040)