Vintage cover, I believe is for the air cover.  Picked this up used over 15 years ago because I collected chrome .  The outer rim has 3 holes for the screws.  Center has a yellow background of the HARLEY-DAVIDSON EMBLEM.   The center has a brass wing spread Egale.   The underside has wear discoloration.   The front chrome and Egale were just polished and are in very nice condition. 

This seems to be a nice old cover,  I can't find any others  that are available.  Please be aware that the yellow behind the eagle has sm painted spots showing the chrome it was painted on.