BUILD STRENGTH, BALANCE & COORDINATION: Toning Exercise Balls are ideal for balance, flexibility & strength workouts; Performing exercises with this small weight ball engages your bodys deepest stabilizing muscles for coordination & maximized strength PVC SHELL UNSTABLE IRON SAND INSIDE: Weighted balls for exercise are durable to function well long-term, iron sand inside creates instability to activate different muscle groups for a leaner & tighter body; Made with PVC coating, do not place toning balls directly on painted furniture as paint may lift & stick to the ball COMPACT AND PORTABLE: Take this small exercise ball or hand exercise ball on your travels for a quick workout; Keep it at the office to stretch and warm up your muscles with a weighted ball during breaks or after a long day at your desk MAKE SURE TO CHOOSE THE APPROPRIATE WEIGHT: Please check these hand exercise balls' size carefully to see whether it fits your hands or not before purchase (for t