Sweden. Military postal stationary Facit Mu1 P , Proof for Mu1 by Jacob Bagges Sedeltryckeri 1916 in lithography, black on grey-yellow paper. Also a very interesting type-writed note in blue "Korrektur d. 5/5 1916" (proof dated May 5, 1916). Some difference in the wording on back "stab, kvarter" instead of "kvarter, stab" as on the issued stationery. The perfect start for a postal stationery exhibit regarding the first Swedish issues of military letters free for the sender. Extremely few Mu1 proofs are known. Excellent quality. Exhibition item!