Widgeons 7.50 dollars multicolored special printing in gutter pair, very fine unmounted mint with 1988 Philatelic Foundation certificate (for strip of 4)" After no. RW51 became void, 15 uncut sheets of 120 (4 panes of 30 separated by gutters) were overprinted "1934-1984" and "50th Anniversary" in the margins. Single stamps from this sheets cannot be identified as the special printing. Gutter pairs are always the special printing