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. Brunswick is excited to introduce the Twist, a new entry performance series that bridges the gap between TZones and Rhinos. Brunswick has a new Twist on ball reaction. We have combined our proven R-16 Reactive with the new Twist Low Diff core to create easy length with a strong and controllable backend reaction on drier lane conditions. Available in 4 vibrant colors and weights 8 through 16 pounds, the Twist is sure to appeal to bowlers of all ages and skill levels. The TwistΓCOs proven cover and performance core combination at a new low price point will be an instant winner for newer bowlers and a great upgrade from plastic balls. Coverstock: R-16 Core Design: Twist Low Diff Core Shapes: Please see pics. There are different core shapes for 8lb balls, 9-11lb balls and 12-16lb balls Finish: 500 Siaair/Crown Factory Compound/Crown Factory Polish Weights: 8 -16 lbs Hook: 80 Length: 190