White-winged Ring-billed Gull

I have been meaning to post this adult Ring-billed for a while. It ranks up there with the most white-winged adult I've personally encountered.

Lake County, Illinois. January.
It shows a large p10 mirror, thayeri pattern on p9 with mirror extending from edge to edge, and an unmarked p5.

Interestingly, it shows a pseudo-mirror on the underside of p10, near the base of the black wedge on the inner web.