A torsion spring is a type of spring that serves to convert torque or rotational force into the form of a spring. Torsion springs are widely used in a variety of products, some of the common ones include:

1. mechanical equipment: torsion springs are commonly used in a variety of mechanical equipment, such as automobile engines, machine tools, airplanes, elevators, etc., to provide torque or rotational force.

2. Furniture: Torsion springs are commonly used in furniture, such as beds, sofas, chairs, etc., to provide support or adjust the seat height.

3. electronic products: torsion springs are commonly used in various electronic products, such as cell phones, cameras, laptops, etc., used to adjust the opening and closing force or rotational force.

4. doors and windows: torsion springs are commonly used in doors and windows, such as door bells, door clips, curtains, etc., used to provide closing force or rotational force.

5. toys: torsion springs are commonly used in a variety of toys, such as spring toys, kites, swing toys, etc., used to provide power or movement force.

6. medical devices: torsion springs are commonly used in a variety of medical devices, such as surgical instruments, bed adjusters, therapeutic instruments, etc., used to support or adjust the function of the instrument.

7. Appliances: Torsion springs are commonly used in a variety of kitchen appliances, such as mixers, ovens, coffee makers, etc., used to provide stirring or rotating force.

8. sports equipment: torsion springs are commonly used in a variety of sports equipment, such as fitness equipment, boxing equipment, yoga equipment, etc., used to provide strength or regulate the instrument.

Overall, torsion springs are a very common and widely used spring, which has an important role in various products, providing the necessary support and power for the operation of the product.