For **agricultural tractors** equipped with **high beam lights**, it is important to know how many they should have. The correct answer is that they should have **two or four** high beam lights.

- **High beam lights** are essential for illuminating a long distance in front of the vehicle, especially on roads outside towns or cities. These lights are mandatory for all vehicles, including agricultural tractors.

- These lights are white and have considerable power, which means they can dazzle other drivers if not used properly. Therefore, it is important for tractors to have an adequate number of lights to ensure good visibility without causing discomfort to others.

- Having **two or four lights** allows for a balanced distribution of light, ensuring that the road is well-lit without concentrating too much light in one spot, which could dazzle other drivers.

In summary, agricultural tractors must have **two or four high beam lights** to comply with regulations and ensure safe and responsible driving.