60 Pfennig on 40 Cent airmail (I), grey-red / turquoise-grey with dark blue typographic imprint, GC paper a, imprint in Type I, with imprint variant Ia: "Distance between 6 and 0 of the value indication, Field 5", postmarked "PROEKULS" on a small piece of mail, flawless condition, examined by Dr. Petersen BPP, very rare stamp, Michel 1. 400.-