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 Our beloved Tropical line has evolved again! The all-new Surge Core, with a boosted differential paired with our dependable Reactor formula will give you the curve you've been craving for. Six exciting colors and fragrances will appeal to just about anybody. Coverstock Type: Pearl Reactive Core Type: Symmetrical Recommended Lane Conditions: Dry to Medium Dry Lanes Reaction Type: Slightly Angular Backend Motion on Drier Lane Conditions X Factor Hook Rating Scale (1-20): 11 Radius of Gyration (RG): 2.58 (15lb) Differential (DIFF): .024 (15lb) Flare Potential: 2-4” Medium Core: Surge Coverstock: Reactor Pearl Reactive Factory Finish: 1500 Grit Polished Color: Midnight Black Fragrance: Amrosia Performance: Value Performance