Detachable collar

A starched-stiff detachable wing collar from Luke Eyres.

A detachable collar is a shirt collar separate from the shirt, fastened to it by studs. The collar is usually made of a different fabric from the shirt, in which case it is almost always white, and, being unattached to the shirt, can be starched to a hard cardboard-like consistency.

Man wearing detachable collar, 1910 USA