Regular Duty vs. Extra Duty Tennis Balls: What’s Actually Different? (Cut Open + Measured)

Regular duty or extra duty? This question keeps coming up in the comments on my individual tennis ball reviews, so I made a full video on it using Dunlop Grand Prix balls. I cut both versions open, weighed them, measured the felt and rubber, and explain which one I actually play with. THE BASIC DIFFERENCE Regular duty balls are known to be softer and lighter with roughly 15 to 20% less felt, made for clay and indoor courts. Extra duty balls are the heavier duty option with more felt, made for outdoor hard courts. CUTTING THEM OPEN The regular duty ball was tougher to cut than I expected, and the extra duty ball was tougher still. A SURPRISE INSIDE The Grand Prix regular duty and extra duty balls use a completely different color rubber. The extra duty core looks like the black rubber you see in the Dunlop ATP Tour and Australian Open balls, while the regular duty core matches a different extra duty ball I cut open earlier. My take: rubber color doesn't matter. It's about consistent thickness and weight, and colors vary between batches anyway. MEASUREMENTS Both balls weighed 58 grams, in line with pretty much every ball on the market. The rubber measured about 4 mm on both. The felt surprised me: about 3 mm on the extra duty ball and about 4 mm on the regular duty ball. WHY THE FELT MATTERS MORE THAN THE THICKNESS The regular duty felt is lighter and woven much more tightly, so it picks up less clay and dust. The extra duty felt is thicker, rougher, looser and fluffs up more. That looser felt creates more air resistance, which is why extra duty balls feel heavier and don't float as much. MY PREFERENCE On clay, regular duty makes sense. On any hard court, including indoor hard courts, I use extra duty and will keep using it. It's a truer feel and it's the ball you'll see in just about every tournament, USTA or UTR match. Regular duty on hard court feels floaty and light to me. This is my experience and it's subjective, so I'd love to hear yours. If you know more about how these balls are made, drop it in the comments. More reviews and more cut-open tennis balls coming soon. CHAPTERS 0:00 Intro: regular duty vs. extra duty 1:05 Cutting open the regular duty ball 1:50 Cutting open the extra duty ball 2:20 Different rubber inside 3:20 Measuring the felt and rubber 4:20 How the felt weave differs 5:15 Conclusions: rubber, weight and felt 6:35 Which ball I use and why 7:30 Wrap-up #tennis #tennisballs #dunlop #dunlopgrandprix #regularduty #extraduty #tennisgear #tennisreview