Features: 1.Material: This true balance toy is made of high-quality materials, use nylon line of good material instead of cheap fishing line. 2.Applicability: This perpetual motion desk toy is very interesting. Newton Cradle never gets old.The concept of Newton39;s cradle is very pleasant.They are great for psychology, science and physics classrooms and are also great for kids. 3.Colorful: This cool things for your room can emit colorful light, the effect is more obvious in the dark, and it is more interesting than ordinary desk toys. 4.Gift: This desk toys for office for adults is an excellent gift. You can give this gift to your children or relatives on Christmas, Halloween, and Thanksgiving. Notice: Actual color may be slightly different from the image due to different monitor and light effect Please allow 1-3cm deviation due to manual measurement Description: Material: glass ball nylon thread electronics Size: 12*9*12cmL*W*H Weight: 180g Battery:4xAA batteriesnot included Package List: 1X Newtons Cradle Balance Balls