The insignia for commissioned officers in the grade of O-2—a single silver bar—is the same across all five branches of the Armed Forces of the United States, but only in the Navy, Coast Guard, and Marines is this insignia worn as collar device. Navy and Coast Guard O-2 officers are designated as Lieutenants (junior grade), while the remaining four branches use the designation 1st Lieutenant.
Though previously authorized for wear on blue and khaki long-sleeve shirts, a 2006 uniform overhaul means that Lieutenants (junior grade) in the Navy are required to wear collar grade insignia only with the shirt that is part of the Service Khaki uniform. O-2 Officers of the Line wear their rank insignia on both collars of the shirt, while Lieutenants (junior grade) serving as Staff Officers wear it only on the right collar point; the left collar point is reserved for their Staff Corps insignia.
In the Coast Guard, the collar grade insignia is mandatory with the Winter Dress Blue uniform, as well as with the Coast Guard Band’s Dress and Ceremonial uniforms. Collar insignia are also worn on the light blue shirt of the Service Dress Blue uniform when the jacket has been removed for work in an office environment.
2nd Lieutenants in the Marine Corps wear collar grade insignia on both collar points of khaki shirts and on the collars of utility and camouflage maternity coats. (Collar insignia is mandatory on khaki shirts even when service and dress sweaters are worn over them.) Officers wearing the Service “A” uniform must wear collar-grade insignia at all times. Guidance on proper placement for collar insignia is found Section 4006 of Chapter 4 of the USMC Uniform Regulations (Marine Corps Order P2030.34G).
Collar grade insignia also pull double duty as headgear insignia in all three services. They are worn on the right side of the Garrison Caps issued by the Navy, Coast Guard, and Marine Corps, and on the Ball Caps authorized by the Navy and Coast Guard.