What is the rank associated with the collar device featuring 2 silver five-pointed stars?

The rank associated with the collar device featuring 2 silver five-pointed stars is Rear Admiral Upper Half. In the United States Navy, the insignia worn on the collar or shoulder boards signifies rank, and for Rear Admiral Upper Half, the two silver stars denote this specific rank.

It's important to note that while the insignia for Vice Admiral and Admiral includes additional stars—three stars for Vice Admiral and four stars for Admiral—Rear Admiral Upper Half distinctly utilizes two stars to represent its rank. The Fleet Admiral rank is a unique position held during wartime and is symbolized by a different collar device, specifically five silver stars. Therefore, the recognition of the collar device with two stars directly and accurately correlates with the rank of Rear Admiral Upper Half.