Features: Make of Plastic material and feature multithreads for uniform pressure release and superior pressure resistance. Automatic return feature that creates a sense of weightlessness when it bounces, it perfect for backflip training. Equipped with detachable and Adjust shoulder Belt, suitable for both kids and adult. Suitable for backflip training and great for waist and abdominal training, yoga assistance, stretching. The exercise ball is suitable for improve postures and relieving lower back, enjoy workout stretches and improve your postures with ease. Specifications: Material: Plastic Color: Silver Gray/Pink Color/Blue Diameter: 45.0cm (17.72inch)/55cm (21.65inch) Package Includes: 1pc Yoga Ball 1pc Inflator Pump 1Pair Belt 1pc Air Plugs 1pc Air Pull note: Please allow 1-2cm errors due to manual measurement, make surely that you not mind before order. Due to difference between different monitors, the picture may not reflect the actual color.