A silver oak leaf is used as collar grade insignia as well as a headgear rank device for commissioned officers in the O-5 grade in the Navy, Coast Guard, and Marines; they are designated as Commanders in the Navy and Coast Guard, and as Lieutenant Colonels in the Marines. (They are also called Majors in the Army and Air Force, but neither service employs collar grade insignia.) The Marine Corps Uniform Regulations give Commanders the option to call for this silver insignia to be replaced with a black one for wear on certain camouflage and utility uniforms.
The number of uniforms for which collar grade insignia was mandated in the Navy was drastically decreased following the 2006 implementation of recommendations made by the service’s Task Force Uniform. With the discontinuation of over a half-dozen working uniforms, today’s Navy seabag contains a lone uniform for which collar grade insignia is mandated: the Service Uniform, specifically the Khaki variant. Coast Guard uniforms for which collar grade insignia are mandated include the Winter Dress Blue, Service Dress Blue minus jacket (for office environments), and Coast Guard Band uniforms (Dress and Ceremonial).
In the Marine Corps, Lieutenant Colonels wear collar insignia with utility and camouflage coats (including the maternity coat) and khaki shirts; collar insignia are a required component of the Service “A” uniform worn by Officers.
These same insignia may also be worn as headgear rank insignia on the Garrison Caps issued by all three of these services and on the ball caps authorized by the Navy and Coast Guard.
Consult your service’s uniform regulations for guidance on how to position on collars and caps.