Demonstrate how machines can reduce work, change the direction, the mechanical advantages of using a multiple-pulley system. The pulley system itself is a fun nice thing to have, the toy is great to simulate how a pull system works, children could definitely learn design and problem solving from this toy. Need children to manually brain, to stimulate children's learning fun, build students' understanding of scientific concepts and channel their into active and meaningful learning experiences. Can raise kid's interest in physics. Student can train their brains and learn more about physics. Features - Color: As shown. - Material: Plastic, metal. - Size: 37.00X15.00X8.00cm/14.54X5.89X3.14in - Demonstrate how machines can reduce work, change the direction, the mechanical advantages of using a multiple-pulley system. - The pulley system itself is a fun nice thing to have, the toy is great to simulate how a pull system works, children could definitely learn design and problem solving from this toy. - Need children to manually brain, to stimulate children's learning fun, build students' understanding of scientific concepts and channel their into active and meaningful learning experiences. - Can raise kid's interest in physics. Student can train their brains and learn more about physics. - Easy to use, environmentally friendly products. - Note: This pulley block does't have dynamometer and weights. Package list: 2 x single pulleys 2 x double pulleys 1 x holder 2 x ropes