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 is excited to introduce a revolutionary ball – actually a game-changer for bowlers seeking alternatives to traditional urethane ball reaction. With recent changes to PBA rules regarding traditional urethane, Hammer took on the challenge of producing a ball that would mimic the performance attributes of the famous Purple Pearl Urethane Hammer without using urethane… and we nailed it. The NU Blue Hammer is “not urethane” but delivers a urethane ball motion, delivering versatility and is smooth, consistent, and predictable, making it ideal for challenging lane conditions. Bowlers will experience all the advantages of a reactive ball that can be used in any competition while benefiting from the classic Purple Pearl Urethane ball motion that has dominated the lanes for years. PERFORMANCE: Mid COLOR: Bad Ass Blue Pearl CORE: LED COVERSTOCK: Not Urethane COVER TYPE: Not Urethane FINISH: 500, 1000 Siaair Micro Pad WEIGHTS: 16-12 Pounds LANE CONDITION: Light to medium oil REACTION: Smooth arc WARRANTY: Two years from purchase date A few tiny pit holes in the cover stock of the ball are normal RG (16lbs)2.541 (15lbs)2.586 (14lbs)2.605 (13lbs)2.598 (12lbs)2.592 DIFF (16lbs)0.035 (15lbs)0.027 (14lbs)0.026 (13lbs)0.025 (12lbs)0.031 A few tiny pit holes in the cover stock of the ball are normal