What is the primary characteristic of a spacer in cargo equipment?

The primary characteristic of a spacer in cargo equipment is size adjustment. Spacers serve an essential function in ensuring that cargo loads are properly secured and fitted within transport vehicles. They help to fill gaps and create a snug fit, which can be critical for maintaining balance and stability during transport. By adjusting the size and configuration of the load, spacers can mitigate movement that could potentially lead to damage or shifting of cargo.

While the other considerations like weight distribution, connector reinforcement, and height extension are important aspects in cargo handling and management, they are not the primary role of a spacer. Weight distribution primarily concerns how the load is balanced within the transport medium, connector reinforcement relates to the strength of connections between cargo components, and height extension involves increasing the vertical space for cargo. In contrast, size adjustment is directly tied to the functional purpose of a spacer, which is to achieve the appropriate dimensions necessary for safe and secure loading.