Which of the following is a typical characteristic of thermal protection?

Thermal protection is primarily designed to manage heat transfer, which can occur in various forms, such as conduction, convection, and radiation. The correct characteristic of thermal protection is that it prevents heat transfer, ensuring that heat does not migrate from one area to another. This is crucial in firestop systems, where controlling the temperature and preventing heat passage can significantly impact fire safety and the effectiveness of barriers.

In the context of firestop applications, materials that provide effective thermal protection are often used to prevent the spread of fire and thermal damage through penetrations and joints in fire-rated assemblies. This characteristic is integral to maintaining the integrity of fire-resistive structures.

The other choices pertain to different properties not primarily associated with thermal protection. For instance, while improving water resistance can be a property of some firestop materials, it does not relate directly to thermal management. Similarly, increasing air flow or reducing sound reflection pertains to ventilation and acoustic properties rather than thermal insulation or protection.