This is your check-in uniform.  You may wear the green barracks cover (depicted) or a green service cap.  

Females may wear either the long or short-sleeve khaki shirt, and green neck tab with this uniform. The service "A" uniform
is authorized for leave and liberty.

The service "B" uniform is the same as the service "A" uniform except that the service coat is not worn. The long-sleeve khaki shirt is worn with the appropriate necktie or necktab. This uniform may be worn as the uniform of the day and for leave and liberty. This uniform will not be worn for formal or semi-formal social events. Most units will where this uniform on the last Friday of every month during winter.  You may also wear the green barracks cover in this uniform. This uniform can be as simple as just the shirt or may include ribbons, marksmanship badges, or breast insignia. 

Commonly referred to as "chucks".  Most units will wear this uniform on the last Friday of every month during summer.  This uniform can be as simple as just the shirt or may include ribbons, marksmanship badges, and breast insignia.  The white crew neck undershirt is optional.