Structure: 

Scissor jacks consist of metal components connected by hinges and screws to form a diamond-shaped frame. When the screw is turned, the frame opens or closes, raising or lowering the height of the jack.

Operation: 

Usually a hand crank is used to turn the screw to raise or lower the jack. Some modern models may have an electric motor that can be operated by pressing a button.

Uses: Mainly used for vehicle repair and maintenance, such as changing tires. Due to its simple design, light weight and easy storage, it is often used as a vehicle tool.

Advantages:

4. 1. It is highly portable and easy to store in the trunk of the vehicle.

2. Simple structure and easy to use.

3. Relatively low price.

Disadvantages:

1. It needs to be operated manually, which may be laborious.

2. It has a limited scope of application and is usually only suitable for light and medium-sized vehicles.

Overall, scissor jacks are a practical and economical vehicle maintenance tool, especially for car owners to use in emergencies on the roadside.