The Seiko Prospex Marinemaster 300 SBDX017 (often called the MM300) is a legendary professional diver's watch, embodying Seiko's mastery of robust tool watches with exceptional build quality. Housed in a substantial 44.3mm stainless steel case (approximately 15mm thick, 50mm lug-to-lug) treated with Seiko's ultra-hard DiaShield coating for superior scratch resistance, it features a unidirectional rotating bezel, screw-down crown at 4 o'clock, and a solid caseback. The bold black dial offers outstanding legibility with large applied luminous markers, broad sword hands, a distinctive lollipop seconds hand, and a date window at 3 o'clock—all enhanced by Seiko's Lumibrite for exceptional low-light visibility. Powered by the in-house Caliber 8L35 automatic movement—a high-performance, 26-jewel caliber derived from Grand Seiko technology—it delivers reliable accuracy (often COSC-like performance), a 50-hour power reserve, and manual winding capability. Water-resistant to 300 meters with a helium escape valve, it's built for serious diving. Paired with a heavy, comfortable stainless steel bracelet and tri-fold clasp, the SBDX017 combines understated elegance with unbreakable toughness—a true icon for divers and collectors seeking Japanese engineering excellence.
Consigned By
This watch is consigned by seller So.
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Watch Details
| Condition & Grading: | New Old Stock, A+ |
| Box & Original Paper: | Yes, Yes |
| Date of Purchase: | 2019 |
| Warranty: | 2-Year Montrez & Co. Warranty |
