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. We’ve taken the benchmark concept and created the next best innovation. The success and longevity of balls like the !Q Tour and Phaze II is no secret, but bowlers are craving more! Enter, the Ion Pro. This is the first asymmetric benchmark ball ever designed by Storm Bowling and will be the new standard of reliability. A benchmark ball is designed to provide a balanced performance across different lane conditions. This ball is designed to allow bowlers to adjust their game without switching to a different ball. Quite simply, it’s made for players of every style from any angle. Every bowler should have this in their bag. The stacked ellipse design of the Element Tour A.I. Core places the smaller ellipses towards the ends of the X-Axis and the widest ellipse at the center of the Y-Axis. Conceptually opposite to cavity designs featured in the Crux™ and Absolute™, the Element Tour A.I. Core dynamics will change more between different layouts with this shape because of it. This center heavy concept places the largest ellipse in the geographic center of the ball. More mass towards the center lowers the RG and, in conjunction with the A.I. Core, makes the Element weight block one of the lowest RG asymmetrical designs Storm has ever had. Normally on asymmetric weight blocks, the thinnest portion creating the asymmetry is very close to the Y-Axis. Stairstep asymmetry is the opposite of that. The widest part is at the Y-Axis which would normally decrease asymmetry, but each subsequent ellipse is offset and skinnier than the previous one which creates asymmetry with each stairstep. Coverstock: TX-16 Hybrid Reactive Weight Block: Element Tour A.I. Core Factory Finish: 4000 Grit Abralon Color: Navy/Carbon/Steel Flare Potential: High Fragrance: Kiwi Twart Weight: 12-16 LBS