Which item is not part of a firefighter's structural firefighting ensemble?

The correct item that is not part of a firefighter's structural firefighting ensemble is a rescue harness. A firefighter's structural firefighting ensemble is specifically designed to provide protection in situations involving direct fire, heat, and hazardous environments typically found in structural firefighting. This ensemble includes critical components such as a helmet, which protects the head from falling objects and heat; an SCBA (Self-Contained Breathing Apparatus), which provides clean air to the firefighter; and gloves, which protect the hands from heat and sharp objects while allowing for dexterity.

A rescue harness, while important in certain rescue operations or high-angle rescue situations, is not typically included in the standard structural firefighting gear. Structural firefighting focuses on ensuring that firefighters have the necessary protection and equipment tailored for combating fires, which makes the rescue harness less relevant in this specific context.