Which two ranks have collar emblems that cannot be switched?

The collar emblems of Gunner and Colonel are unique in that they represent distinct roles within the Marine Corps hierarchy, which prevents them from being interchanged. Each rank has a specific emblem associated with it that signifies the level of responsibility and authority.

The Gunner, typically a senior enlisted rank in the Marine Corps, is represented by a distinct emblem that indicates expertise in a particular occupational field, often in weapons and equipment. On the other hand, the Colonel is a field grade officer rank, indicated by its own distinct insignia that reflects command and leadership responsibilities at a higher organizational level.

Because these two ranks serve very different functions and their insignia carry specific meanings representative of their respective ranks, they cannot be switched. This clear delineation in rank insignia maintains the structure and hierarchy within the Marine Corps, ensuring that each rank is properly represented by its unique emblem.