A device that demonstrates a pendulum, and shows the law conservation of energy. A fantastically relaxing object to have ticking and clicking away as you are working, play or rest. Made of metal and ABS plastic material, it is bright, preservative and rust-proof. There are three sizes to choose from: S, M, L. It is suitable compatible office, home and other indoor places. Item Name: Newton Cradle Material:ABS,Metal Size Details: [Our Size S] Length: 8.5cm/3.3", Width: 7cm/2.8", Height: 9cm/3.5" (Approx.) [Our Size M] Length: 13.5cm/4.9", Width: 11.5cm/4.5", Height: 13.5cm/5.3" (Approx.) [Our Size L] Length: 18cm/7.1", Width: 15cm/5.9", Height: 18cm/7.1" (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 Newton Cradle