What are the indentations on the lugs of threaded couplings called that assist firefighters in coupling fire hoses?

Higbee indicators are the specific indentations on the lugs of threaded hose couplings designed to assist firefighters in properly aligning and coupling fire hoses. These indicators help ensure that the hose couplings fit together smoothly and also allow firefighters to quickly identify the correct alignment during stressful and time-sensitive situations.

Understanding the function of Higbee indicators is crucial, as it reduces the potential for cross-threading, which can lead to leaks and malfunctions during operations. The other terms, such as grooves, threads, and notches, although related to hose design, do not have the same precise role as Higbee indicators in the context of ensuring a proper connection between couplings. The distinction of Higbee indicators lies in their unique design specifically intended for use in firefighting scenarios.