Made of high quality TPR material, thick thermoplastic rubber. Very durable, has high tear resistance and can withstand a lot of squeezing. It is 2.5 inches in length making it very suitable for all sizes of hands.These stress relief balls help alleviate stress and anxiety in children and adults. Enjoyable relaxation aid, they can help people with autism and ADHD. It is also good for strengthening hand, wrist forearm muscles, and ideal for rehabilitation and physical therapy.