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. Hammer has been on a roll and is ready to continue the momentum with the Envy Tour Pearl. Envy Tour has quickly become a staple in the Hammer line; the unique core numbers and motion differ from anything on the market. We are excited to expand the line and introduce an Envy Tour that is longer, needs less oil, is still predictable, and always makes the move on the backend. The addition of HK22 poured in a chrome color, along with the performance you’d expect from an Envy Tour, makes this piece a must-have for every Hammerhead out there. Performance: High Color:Chrome Core: Obsession Tour Coverstock: HK22 - Envy Pearl Cover Type: Pearl Reactive Finish: 500, 1000, 1500 Factory Compound Weights: 12-16lbs Lane Condition: Medium Oil Reaction: Length With Strong Backend Warranty: Two Years From Purchase Date Radius of Gyration(RG): 16lbs - 2.484; 15lbs - 2.469; 14lbs - 2.485 Differentail (Diff): 16lbs - 0.029; 15lbs - 0.034; 14lbs - 0.034 Intermediate Diff: 16lbs - 0.011; 15lbs - 0.013; 14lbs - 0.013