Shoulder sleeve insignia (SSI) are cloth emblems worn on the shoulders of US Army uniforms to identify the primary headquarters to which a soldier is assigned. Most military units smaller than brigades do not have SSI, but rather wear the SSI of a higher headquarters. Insignia of units that are no longer active can be found at Obsolete shoulder sleeve insignia of the United States Army.
Army elements to joint commands / joint forces
Commands / field armies / corps / other
Cavalry regiments
Civil affairs commands
Explosive ordnance groups
Military intelligence groups
Multi-domain task forces
Regional support groups
Schools and centers of excellence
Special operations units
Sustainment commands (expeditionary)
Theater sustainment commands
Training centers
See also Field army insignia of the United States Army Corps insignia of the United States Army Division insignia of the United States Army Brigade insignia of the United States Army Obsolete shoulder sleeve insignia of the United States Army
References
The US Army Institute of Heraldry