This is the official 2023–24 third football jersey of Athletic Club Bilbao, manufactured by Castore. The shirt features a striking geometric wave-pattern print in shades of gray and light lavender across the torso, evoking modern architectural motifs—consistent with Bilbao’s identity as a city of avant-garde design (e.g., Guggenheim Museum). Constructed from high-performance moisture-wicking polyester, it ensures breathability and comfort during intense matches or casual wear. Key branding includes the Castore eagle logo on the left chest, the Athletic Club Bilbao crest on the right, and main sponsor 'Kutxabank' prominently displayed center-front in bold black-and-white lettering. The raglan sleeves are light gray with black side panels for visual contrast and enhanced mobility, while the crew neck has a black ribbed trim. A LaLiga patch ('B' for Basque region) appears on the left sleeve, and a small Castore authenticity tag is sewn at the lower left hem. Ideal for fans, matchday attendance, or streetwear styling, this jersey blends athletic functionality with contemporary aesthetic appeal. Lightweight, stretchable fabric offers unrestricted movement, making it suitable for training, travel, or everyday urban wear in mild to warm seasons.