Collar size .......16 1/2" (to fit shirt size 16")
Vintage collar, over half a century old, but still in fairly good condition.
It has discoloured with age, along the fold line, and (unless you are going to wear it just for a theatrical costume or similar), you would probably need to have it relaundered and restarched before use.
There are a couple of age spots on the inside of the collar, and an unsightly mark where the previous owner's laundry mark has been removed. These will not show when you are wearing the collar.