These classic definitive stamps of Luxembourg feature a finely engraved portrait of Grand Duke William IV (1905–1912), who ruled during the early 20th century. Issued between 1906 and 1914, the series presented his likeness framed within an ornate oval with oak leaves. The denominations shown are 25 centimes (blue) and 30 centimes (olive-green), both printed in typographic style with clear denomination markers in the lower corners.

The issue is notable for its detailed engraving and was released during a period of modernization in Luxembourg. Stamps from this set were widely used on domestic and foreign mail until superseded by later issues under Grand Duchess Marie-Adélaïde. Today, they are appreciated by collectors for their historical significance and their role in the evolution of Luxembourg’s definitive series.