Description: Wood material, effectively absorbs sweat from hands and prevents slipping. The surface is uneven, it is easier to get trigger point massages for hand. Rotated repetitively in the hand to get Hand exercise, massage the palm, relieving stress, improve joints, improve manual dexterity and strength Small and delicate, portable, great gift for office white-collar workers, retired, elderly people Good for trigger point massages, spiky knobs give a deep tissue massage Specification: Material: Wood Diameter: Approx.4.5cm/ 1.8 inch Package Includes: 4 Pieces Hand Exercise Balls Note: Size for manual measurement, there may be a 0 to 1 cm error, belongs to the normal phenomenon. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!