25c light blue 'Hidalgo' postal stationery envelope (UPSS #E9, H&G 9b) with '5381' number and 'ACAPULCO' district opt used with somewhat blurred strike of undated oval FRANCO EN OMETEPEC cancel in black with purple 'Miahuatlan, Juan F Sierra' manuscript endorsement at left. Addressed to MEXICO CITY with small part arrival mark on reverse. Backflap missing and a few peripheral opening tears at top but a scarce & unusual use.