There are four issues of SkyWest Airlines wings however, the differences between the 2nd Issue and the 3rd Issue are small but distinctively different. The differences on the obverse are mainly the engraving of the wreath and the way the center logo is mounted. These differences would barely show up in a scan. The difference on the reverse is that the 2nd Issue has no hallmark whereas the 3rd Issue is hallmarked "CWS". Because the difference will not really show up in the scan, we have decided to not include the 3rd Issue in the listing of this airlines.