Vintage detachable semi-stiff collar, made around the 1940s.   
You will need a pair of collar studs to fix this collar to your tunic shirt.  These studs are NOT included, but are available separately.

Size: Collar size 16.

Condition: Vintage collar, made in mid-20th century, but never used and in good condition, except for two tiny spots on the lower edge, as shown.