Seiko Prospex Speedtimer Automatic black dial steel bracelet 39,5 mm

Collection Speedtimer

The Speedtimer holds a unique place in Seiko’s history and in the story of the modern chronograph. In 1969, the Japanese brand made history by unveiling the Caliber 6139, one of the very first automatic chronographs equipped with a vertical clutch and column wheel — a technical feat that would forever shape the world of sports watches.

The current Prospex Speedtimer line draws inspiration from this racing heritage, reinterpreting the codes of the 1970s with a contemporary approach. More than a simple nod to the past, it offers watches designed for enthusiasts of precision, reliability, and functional design.

The SPB515 perfectly illustrates this vision. Unlike the most famous Speedtimer models, often associated with chronographs, this reference adopts a three-hand with date configuration, enriched by an internal countdown bezel. This complication, directly inspired by competition instruments, allows intuitive measurement of short intervals — whether for the start of a race or a simple everyday marker. Blending heritage and modernity, the SPB515 embodies a more streamlined interpretation of the Speedtimer DNA.

Design & Aesthetics

The Seiko Prospex Speedtimer SPB515 impresses with its black dial, sober and functional, reinforcing its sporty identity. Applied, sharp, faceted indexes are accented by luminous plots ensuring optimal legibility in all conditions. The hands, also coated with LumiBrite, stand out strongly against the dark background, ensuring instant readability even in low light. The seconds hand is distinguished by its orange tip, a sporty detail echoing the last 15 minutes highlighted on the internal bezel scale.

This internal rotating bezel, operated by an additional crown at 4 o’clock, is one of the model’s signatures. Inherited from the spirit of competition instruments, it allows easy countdown tracking. Its seamless integration into the case helps preserve the purity of the lines.

The stainless steel case, treated with a super-hard coating, measures 39.5 mm in diameter and 12 mm thick. Compact and balanced, it reprises the angular codes of the 1970s Speedtimers but with modernized proportions that ensure comfort and versatility. Alternating polished and brushed finishes create subtle light effects, enhancing the refinement of the design.

The watch comes on a vintage-style multi-link steel bracelet, reminiscent of 1970s Jubilee-style bracelets. Flexible and ergonomic, it closes with a secure push-button folding clasp, ensuring comfort and practicality for daily wear.

Movement & Performance

At the heart of this Speedtimer beats the in-house Caliber 6R55, reflecting Seiko’s expertise in designing robust and reliable mechanical movements. From a recent generation, it delivers an extended power reserve of 72 hours — a full three days — allowing the watch to be left aside for a weekend without stopping.

Main technical features:

• Type: Automatic with manual winding option
• Frequency: 21,600 vibrations/hour (3 Hz)
• Jewels: 24
• Power reserve: approximately 72 hours
• Functions: hours, minutes, seconds, date at 4:30

The hacking seconds function allows for precise time setting, an appreciated feature for detail-oriented enthusiasts.

Although Seiko officially states a tolerance between –15 and +25 seconds per day, many users report better real-world performance, underscoring the stability of this movement. Built to withstand everyday challenges, it also offers magnetic resistance up to 4,800 A/m, reinforcing its reliability in modern environments filled with electromagnetic fields.

By combining historical heritage, contemporary technology, and proven robustness, the 6R55 makes the SPB515 a versatile mechanical watch, capable of accompanying its wearer both in daily life and in more demanding situations.