When inspecting coupling devices, what specific feature should be checked?

The tightness of the connection is a critical feature to check when inspecting coupling devices. A secure connection between the trailer and the towing vehicle is essential for safe operation. Loose or improperly connected coupling devices can lead to detachment while driving, potentially resulting in accidents or loss of control. Ensuring that the connection is tight helps maintain stability and safety on the road.

While the other options may seem relevant in different contexts, they do not directly address the fundamental safety feature of the coupling devices. The color of the glad hands, for example, does not impact their functionality or security. Similarly, the size of the trailer and the weight of the truck are important factors for overall vehicle operation and regulations, but they do not pertain specifically to the integrity of the coupling connection. Therefore, focusing on the tightness of the connection is paramount for safe driving practices.