Perforated Official stamps. 1938-42, Monoplane over Steamer 6c blue and R.C.A.F. Training Plane 6c deep blue, two-line perfin ''O.H.M.S.'', two three-side margin (bottom part of a sheet) plate No. blocks of 10 (5x2), perfect condition, full OG, NH, VF and a spectacular unit, Est. $100-$150 (Image)