Zekrom-GX, a Holofoil variant from the SM Black Star Promos set, holds the promo number SM138 and is categorized as a Promo rarity card. Currently valued at $19.98, it reflects the demand for powerful Pokémon cards in competitive play and collection. Its unique GX attack and striking artwork contribute to its appeal among collectors, making it a notable addition to any Pokémon card collection.