The igelball, also known as a hedgehog or massage ball, is a popular massage product used for self-massage and partner massage. It is an air-filled ball with pleasant nubs that promote blood circulation, flexibility, and relaxation. The ball is commonly used for hand and finger massage, as well as for reflexology massage. While the specific ingredients or materials of the igelball are not mentioned in the provided search results, it is typically made of durable, non-toxic materials. As for user feedback, the positive aspects include its effectiveness for promoting blood circulation and relaxation, while some users may find the nubs uncomfortable during use as a potential downside. For specific information on the ingredients or materials, it is recommended to refer to the product packaging or contact the manufacturer directly.