Small parcel label from a coffee sample bag with 'MUESTRA SIN VALOR' and 'MUESTRA DE CAFÉ COFFEE SAMPLE' handstamps on front franked on reverse with 1935 5c brown & blue and 3 x 1939 1c olive green with '1939' overprint (SG 297a & 399) tied by SERVICIO INTERNACIONAL CORREOS GUATEMALA C.A. cds dated 11 MAY 1939. Addressed to UK. An unusual use and rate.