The SPB505 belongs to the Seiko “Prospex Alpinist” line — a model family whose roots trace back to the original field/sports watches Seiko made for mountaineers and explorers (first introduced in 1959).With SPB505, Seiko continues that “adventure + heritage” spirit: a watch meant for rugged outdoor use (hiking, travel, exploration) — while refining styling and materials for modern daily wear. The design leans toward classic field-watch aesthetics: simple, functional, yet timeless — making SPB505 a versatile pick whether you’re outdoors or in the city.