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 Rattler NU takes advantage of the new chemistry in cover stocks Not Urethane (NU). This chemistry allows us to create a unique urethane motion without the pitfalls of a urethane ball. The Rattler NU features the original Rattler core with an RG of 2.480 and a differential of 0.035, giving you a medium DIFF core and a unique cover. The Rattler NU is a great addition to the Rattler lineup, yielding a smooth, controllable, continuous ball motion that allows you to control the backend of the lane. Level: Reliable Color: Teal Core: Rattler Symmetric Coverstock: Not Urethane Cover Type: Not Urethane Finish: 500, 1000 Siaair Micro Pad Weights: 16-12lbs Rg: 2.480(15lbs) Diff: .035(15lbs) Warranty: Two years from purchase date