Which insignia has a rating designator associated with it?

The insignia that has a rating designator associated with it is the E-4 Petty Officer Third Class. In the United States Coast Guard, enlisted personnel receive rating designators once they achieve the rank of Petty Officer. This means they have completed specific training in a particular field and are recognized for their technical expertise. The E-4 rank represents an advancement beyond the previous ranks, which do not carry associated rating designators.

In contrast, the ranks of E-2 Seaman Apprentice and E-3 Seaman are considered non-rated positions. Individuals in these ranks have not yet specialized in a specific role or rating within the Coast Guard, thus they do not possess a rating designator. This distinction highlights the progression within the enlisted ranks, where advancement to the Petty Officer levels signifies a commitment to a specific Occupational Specialty and an increase in responsibility.