10c black on green 'Cubierta' (H&G CC37) used from MEDELLIN to BOGOTA. Insured for 200 pesos with BOGOTA arrival mark dated MAR 1 1906 on front. The Cubierta was kept as a receipt with the envelope flap still attached to the reverse with boxed SECCION 7a RECOMENDADOS marking dated FEB 19 1906 on the reverse. Unusual.