These bowling balls require drilling. Available in 5 sizes, the drill size is based on the ball weight. X-Small: 6 lbs - 8 years and under, Small: 8 lbs and 9 lbs - Ages 8 - 11 Years, Womens Ring Size 8 - 11 Years, Medium: 10 lbs, 11 lbs, 12 lbs, 11 - 15 Years, Adult Ring Size 10 - 15 Years. Bottom, Large, e: 12 lbs and 14 lbs, Mens Ring Sizes 10-12 or Big Hand, XL: 15 lbs and 16 lbs, Mens Ring Sizes 13 years and up or very large hands. If you would like a different size drill for the weight selected, please email us immediately once you include your order number. The pre-drilled bowling balls are not returnable or exchangeable. Having a spare is always a good thing. T-Zones are very affordable. Choose your favorite color or two, and three. Perfect ball for kids, beginners and extra shooting. This ball glows under black light. Picture 2 shows under black light. Coverstock: Plastic/Polyester Ball Color: Many Colors Available - The product color of this ball is listed in the title of this ball. Finish: High Gloss Polish Hook Potential: 25 (Low) Low-High on 10-175 Scale Recommended Lane Conditions: All