Fun and educational: Newton's pendulum is a great tool for students to understand Newton's laws of motion and for teachers to use in physics classes. Longer swing time: The resistance of the air allows the balance ball to continue moving for 10-20 seconds, providing ample time to observe kinetic energy. High quality materials: Solid wood base, fishing wire, and stainless steel metal balls make this Newton cradle durable and long-lasting. Desk decoration and stress reliever: This unique gadget serves as a special decoration for your office and home, while also providing a relaxing and stress-relieving activity. Unique gift idea: Perfect for kids, adults, and science enthusiasts, this nostalgic toy makes a great gift for birthdays, Christmas, and other holidays. Item Name: Balance Ball Decor Material: Wood, Metal Category: Ornaments Features: 7 Balance Balls, Black Base, Fun Size Details: L: 23cm/9.06", W: 14cm/5.51", H: 17cm/6.69" (Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 1 x Balance Ball Decor