Seiko 5 Sports SRPG63 Nylon watch

Seiko SRPG63 Cement Boy

The 5 Sports SKX series took the bones of Seiko’s legendary dive watch and built something more versatile. The SRPG63—nicknamed “Cement Boy” by collectors—strips away the dive bezel complications in favor of a clean, field-watch aesthetic in muted gray.

Built Like a Seiko Should Be

The 40mm stainless steel case hits that sweet spot where it wears substantial without taking over your wrist. Inside, the 4R36 automatic movement offers 41 hours of power reserve and hacking/hand-winding—features that used to cost considerably more. At 100 meters water resistance with a screw-down crown, it handles real life without drama.

The Cement Aesthetic

That gray dial earned this watch its nickname. It’s not quite silver, not quite charcoal—it’s the color of architectural concrete, which sounds strange until you see how it catches light. The gray nylon strap completes the monochromatic look and makes more sense than a bracelet for a watch you’ll actually wear hard.

What You’re Getting

Hardlex crystal (serviceable, not sapphire), day-date complication at 3 o’clock, and Seiko’s LumiBrite on the hands and indices. The see-through caseback lets you watch the 4R36 do its thing—24 jewels ticking away at 21,600 vph. It’s not a chronometer, but Seiko’s track record with the 4R calibers speaks for itself.

The Bottom Line

The SRPG63 works as a daily beater, a mod platform, or just a solid automatic for someone who wants Seiko quality without the dive watch commitment. The Cement Boy earned its nickname—it’s industrial, understated, and built to actually get worn.