5c blue 'Momotombo' postal stationery envelope (H&G B45) used with good strike of AGENCIA POSTAL DE BUENOS AIRES oval cancel dated NOV 8 1904. Addressed to MANAGUA with small oval CARTERO No. 4 - 5 P.M. MANAGUA marking on front and RIVAS & MANAGUA oval transit marks on reverse. Cover a little worn at left but a very rare origination.