Very nice Kid's VINTAGE shirt !! 
The label says 8. 
It will be a wonderful 50's (or mid-century) outfits collection.
There is a small snag on a sleeve from the factory (please confirm at the last photo).
The measurement: I noted the inches in a photo.

Please zoom all photos carefully to see their condition. 

The color may vary due to the devices/monitors and reflections. 

Please ask if your have questions, doubts and/or concerns since I may have a mistake by accident. Thank you for watching.