Product Introduction: Gimniku 45: The perfect balance ball for fitness and training, it is extremely durable with a load capacity of 66.1 lbs (300 kg). The most effective gimnikine training ball as the action is clearly transmitted to the body as you work on a firm and hard-textured ball. It is used in a variety of fields, and is very effective for building strength as well as balance. (Japan G Ball Association Certified Ball) This product is certified by the NPO Corporation Japan G-Ball Association as it is recommended for safety and durability when used for exercise. Japanese School Association Certification Ball: This product is approved by the Japan Athletic Research Association Association. Size: Maximum Diameter: 17.7 inches (45 cm); Color: Yellow; Recommended Age: 3 years and up; Made in Italy; Material: Polyvinyl chloride (no phthalate plasticizers); Air pump sold separately. Precautions for Use: The diameter shown on the product page is the maximum diameter. Due to the characteristics of the load-bearing material, the ball is stiff at first and may not inflate to the maximum diameter at a time. If you want to close to the maximum diameter, please take a little time (about 5 times per hour).