What feature of recessed lugs sets them apart in terms of design?

Recessed lugs are characterized by their design of being shallow holes that are drilled into the coupling. This specific feature creates a space for the connection point, allowing for a more streamlined and less protrusive design compared to other types of lugs. The benefit of having recessed lugs is that they can prevent snagging and catching on other equipment or obstacles, which enhances operational efficiency in the field.

The use of shallow holes means that the lugs can still effectively serve their purpose without extending excessively from the coupling, providing a cleaner profile. This design consideration is essential in ensuring that fire suppression equipment is both functional and practical, especially in tight spaces or dynamic environments where firefighters operate. The other aspects mentioned in the choices do not accurately describe the distinctive quality of recessed lugs.