Half wing AG

[mechanicdar]

Hello

I am new to the forum, and I have a question I am hoping someone on here can answer for me please. I picked up a half wing AG brevet today. I know normally they have the wing the reef and the AG in the center. This one tho has all that but also a crown and a RAF at the bottom, and I am wondering why ? i know RAF stands for royal air force. I am just curios to know why this one has that and others I've scene on uniforms do not.

thanks