The Kreider-Reisner KR-21-A was a 1928 American two-seat monoplane. They were designed and built by the Kreider-Reisner Aircraft Company of Hagerstown, Maryland.[1] Fairchild Aircraft took over Kreider-Reisner in 1929 and continued to build them, as the Fairchild KR-21, later the Fairchild 21.[2][3]