What device is used for lowering heavy loads and is made of aluminum?

The correct choice is based on the nature and purpose of the device mentioned in the question. A brake tube is designed to control the descent of a load, providing a system to lower heavy items safely and effectively. Its construction from aluminum allows for a combination of strength and light weight, which is crucial in applications where minimizing weight is important while still needing to support significant loads.

Other devices mentioned, such as a hoisting device, typically involve lifting and may not specifically focus on lowering loads in the same manner as a brake tube does. A rope gripper and a load controller might manage tension or the operation of a rope or load but do not inherently deliver the same lowering function as a brake tube designed specifically for that purpose. Thus, the attributes and intended use align clearly with the brake tube as the correct answer.