MarchMore Newton's Cradle, Balance Balls Desk Science Toy Gift &lt;BR&gt;Not only demonstrates a pendulum, but also shows the Laws of Conservation of Momentum and Energy.&lt;BR&gt; &lt;BR&gt;Friction and damping effects are also observed.&lt;BR&gt; &lt;BR&gt;Often used as a toy to amuse people&lt;BR&gt; &lt;BR&gt;Includes steel balls, plastic frames and base&lt;BR&gt; &lt;BR&gt;Package Included: 1 x Newton's Cradle Balance Balls Desk Toy