It should be noted that in the Marine Corps Gunnery Sergeants are either promoted to Master Sergeant or First Sergeant. Master Sgts stay in their field of specialty while First Sgts hold more of an administrative billet, not limited to their field, on the company level. Master Sgts are promoted to Master Gunnery Sergeant and First Sgts are promoted to Sergeant Major. Sergeants Major hold billets from the battalion level on up. The senior enlisted man in the Marine Corps is the Sergeant Major of the Marine Corps.