What does the term "rocker" refer to in Marine Corps rank insignias?

The term "rocker" in Marine Corps rank insignias refers to a device indicating additional ranking levels. This is specifically displayed as a strip worn below the rank insignia, signifying a progression or advancement in rank. For example, as a Marine is promoted, they may receive additional rockers to denote their experience and rank adjustments.

This designation provides clarity within the military structure, allowing for immediate recognition of the member's status and experience level. The "rocker" is an essential element that aids in distinguishing ranks, contributing to efficiency and order within the ranks.