Material - Bouncy string balls are made of solid, high density and natural rubber, which attached to an adjustable hook and loop wrist band with a stretchable cord. High resilience material and durable construction can strengthen elasticity of ball, extend the useful life. Size Measurement - Bouncy string ball is approximately 6.3cm in diameter, 87 grams in weight. Small handy size, easy to throw and catch. Wrist band approximately 9" / 22.5cm in length. String approximately 98cm in length. Training Aids - for baseball and hockey ball catching practice. Finger movement training can promote brain development. Bright colorful balls stimulate visually, enhance fast response to quick movement. Perfect for beginner early development, help hand-eye coordination. Arise interest in sport, grow up healthily in happiness. Rehabilitation Training Tool - For hand finger stiffness relief and wrist exercise suitable. Dangle from a string attached to a wristband, NEVER lost the ball again! Idea tools for early rehabilitation training help hand sensory restoration.