So if you have a young gymnast in your life, this Sasaki M-20B ball is exactly what they need for practicing rhythmic gymnastics. The 17cm diameter (about 6.7 inches) makes it the perfect middle size - not too big for smaller hands to control, but substantial enough to practice proper techniques. The light blue color is vibrant and easy to see during routines, which is helpful for both practice and performances. What's really important is the quality - Sasaki is known for making professional-grade gymnastics equipment, and this ball has the same quality as their more expensive 'Gym Star' line but at a more affordable price point. The rubber material has just the right amount of grip without being sticky, and it holds its shape well. One thing to note - you'll need to use their M-22P ball pump to get the air pressure just right. Don't over-inflate it, as that can stretch the rubber and affect the ball's performance. This particular model doesn't have the official certification mark, so it's perfect for practice and training rather than competition. I've bought several of these for our gym's beginner classes, and they've held up really well to daily use. The kids find them easier to handle than full-size balls while still learning the proper techniques. If you're looking for a quality practice ball that won't break the bank but will still withstand regular use, this Sasaki one is definitely a solid choice.