This is a very nice cover that was mailed on the day the new 5-cent airmail postage rate went into effect in 1928. It is a bi-color printed cachet that says "Via Air Mail" and "Use the Overhead Mail" in blue and red. It has Scott C11 on it, and was postmarked in Bay City, MI on August 1, 1928. Scott C11 was issued 6 days earlier.