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 Centroid symmetric core addresses a need that many value performance balls struggle with…a lower density. By shifting the weight more towards the center of the ball we have eliminated the over/under that many balls in this category struggle with. The Burners have been purposely engineered to give you a reliable reaction when the lanes have broken down. Color: Amethyst / Red Coverstock: S62 Pearl Weight Block: Centroid Symmetric Factory Finish: 1500 Grit Polished Flare Potential: 3-4 Radius of Gyration (RG): 15lbs – 2.53 Differential (Diff): 15lbs – 0.039