Belgian Customs Seal, Antwerp, Image & Found by Bart Wils
Found in Belgium, ?mm.
One side has the lion rampant on a crowned shield from the Royal Belgium coat of arms as of 1837 (this is the 'lesser arms' used by the Government) with ROYAUME DE BELGIQUE circling it. On the other side is ANVERS which is French for Antwerp curved above the number 24 and (ENTREPOT) curved below. Entrepot (originally a French word for warehouse) is now used as a term to signify a customs area.
Probably around the edge is the word DOUANES which is French and Dutch (satisfying both the main languages of Belgium) for border control customs.