Paraguay, Scott C175 variety, MNH.  1948 10g dark green & brown Air Mail commemorating 50 years of Episcopalians in Paraguay, choice sheet margin block of 8 contains 4 inverts and 2 tete-beche pairs with normal stamps, light offset on back of a few stamps, perf seps in top margin not affecting the stamps, fresh, bright, well centered, F-VF.  Unlisted and unique showpiece. 

Only 25 inverts exist, 5 of which are in se-tenant pairs with a normal stamp.