This is the official 2023–24 third match jersey of Athletic Club Bilbao, manufactured by Castore. The jersey features a vibrant royal blue base with an intricate geometric sublimated pattern across the front and sleeves, adding depth and modern aesthetic appeal. It has a V-neck collar with white trim and red dotted piping detail, enhancing contrast and sporty elegance. The left chest displays the Castore brand logo—a stylized winged 'V'—while the right chest bears the iconic Athletic Club Bilbao crest: a shield with red-and-white vertical stripes, green tree, and gold lion. Centered on the torso is the main sponsor 'Kutxabank' in bold white lettering with black outline and distinctive red dot on the 'K'. The inner neck label confirms Castore as the technical supplier, and a small Castore authenticity tag appears on the lower left hem. Made from lightweight, breathable performance fabric with moisture-wicking properties, this jersey ensures comfort during matches or casual wear. Ideal for fans supporting the Basque club, it blends authentic football heritage with contemporary design. Perfect for matchdays, streetwear styling, or everyday sporty outfits in warm seasons.