Package Include 1 x Set of Physical Teaching Characteristics - Let the metal ball pass through the ring several times to show that the metal ball can pass through the ring at normal temperature. - Heat the metal ball for 3- 5 minutes, and then pass the metal ball through the ring. - Size: About 23.00X4.50X3.00cm/ 9.04X1.77X1.18in - Design to prove the effect of thermal expansion and contraction. - Material: Plastic, metal - Color: As Shown - At this time, the metal ball expands due to heat, so it cannot pass through the ring. - Great physical teaching for teacher. Goods Information Are you looking for a professional, affordable physics experimental kit? Are you in search of a sturdy, tool that can help junior know the basic physical knowledge? If yes, look no further! Our professional physics experimental kit must meet your needs.