The Pure2Improve Massage Ball set includes three different sizes: small, medium, and large. Each ball has a different density and Colour: yellow (soft), red (medium), and black (firm). These massage balls are made of plastic and weigh 200g. The massage balls are designed to release built-up tension by applying focused pressure to specific muscle trigger points or knots. This can help alleviate pain, prevent injury, and improve performance. They are also great for trigger point release and acupressure massage, targeting muscles for myofascial release. Use the different sized balls depending on the area of your body you want to work. The set is a great tool for at-home or on-the-go self-massage. Pure2Improve 3 Massage Balls Dia (5 CM) in Black