This lunch box typically consists of a container made of heat-resistant materials such as plastic or stainless steel, with an electric heating element inside. They often come with a detachable power cord that can be plugged into a standard electrical outlet or a car's cigarette lighter socket for heating.

This electric food warmer or portable food heater, is a device designed to heat up pre-cooked food or keep it warm until it's ready to be eaten. It's particularly useful for people who need to bring their own meals to work, school, or while traveling. 

1. Portability: Electric lunch boxes are designed to be portable, allowing you to carry your hot meal wherever you go. This is especially useful for individuals who work in environments without access to microwaves or stoves.

2. Convenience: With an electric lunch box, you can heat your food quickly and easily, eliminating the need to find a microwave or stove. This saves time and hassle, especially during busy workdays or when traveling.

3. Versatility: Electric lunch boxes often come with multiple compartments, allowing you to heat up different dishes simultaneously. This is convenient for those who enjoy variety in their meals or need to pack separate items such as rice, vegetables, and meat.

4. Energy Efficiency: Compared to conventional stoves or microwaves, electric lunch boxes typically consume less energy, making them more environmentally friendly and cost-effective in the long run.

5. Temperature Control: Many electric lunch boxes come with adjustable temperature settings, allowing you to control the level of heat applied to your food. This ensures that your meal is heated evenly and to your desired temperature.

6. Safety: Electric lunch boxes are designed with safety features such as automatic shut-off mechanisms to prevent overheating and ensure safe usage.

7. Healthier Eating: By bringing your own meals from home, you have better control over the ingredients and portion sizes, promoting healthier eating habits. Electric lunch boxes allow you to heat up homemade meals rather than relying on pre-packaged or fast food options.

8. Cost Savings: Over time, using an electric lunch box can save you money compared to buying lunch from restaurants or cafeterias on a daily basis. Additionally, preparing your own meals allows you to buy ingredients in bulk and cook in larger batches, further reducing costs.