Registered airmail cover from GUATEMALA CITY with typed return address on front franked with 1963 10c olive brown and 20c blue (SG 686 & 688) tied by CENTRAL DE CERTIFICADOS CORREOS NACIONALES '8' cds in blue dated 30 DIC 1966 with fine CORREOS DE GUATEMALA AMBULANTE GUATEMALA - PUERTO BARRIOS 1c red METERMARK alongside and registration marking below. Addressed to AUSTRIA. An unusual Ambulante metermark.