The "Bar Wing" 1889 Silver Dollar is one of the Top 100 Morgan varieties, which places it near the pinnacle of the myriad VAM varieties. The "Bar" is a raised blob of metal that sits atop the eagle's wing just below the N of "IN GOD WE TRUST." The blob is the result of a small piece of the die that broke off. When subsequent coins were struck, metal flowed into the hole in the die, creating the "bar."
Fortunately, the Bar Wing is a relativly common variety, with ample supplies in Mint State from MS62 to MS64. The best example of which we are ware is the colorful PCGS MS66 illustrated above.