This timepiece is a magnificent artifact from the late 1960s to early 1970s, an era where Tissot redefined the sports watch with the "PR" (Particularly Robust) designation. This reference is defined by its substantial stainless steel case and a breathtaking deep charcoal or navy racing dial that features the iconic floating indices—a design where the hour markers are suspended above the dial, allowing the hands to pass underneath for a stunning 3D effect. It is powered by the legendary Caliber 784-2, a high-performance automatic engine engineered with a specialized "shock-absorber" mounting system to withstand the high-vibration environment of a professional cockpit.

The architecture is quintessentially motorsport, utilizing a robust tonneau-style case and the signature "GT" perforated steel bracelet, which was inspired by the steering wheels of period sports cars. The dial is a work of high-intensity functional art, featuring bold baton hands and a high-contrast date window, all protected by a domed hesalite crystal that adds a warm, vintage glow. Flipping the watch over reveals the crisp Tissot engravings and the solid "Seastar" heritage, definitively confirming its authentic Swiss pedigree. This is an essential acquisition for an elite collector who appreciates racing history, the mechanical soul of a 21-jewel heart, and the bold, indestructible presence of the Tissot PR-516.