Prospex
Seiko’s "Professional Specifications" line — the company’s tool-watch heritage, traced from the 1965 62MAS first Japanese dive watch through the 1970 6105 "Willard" through the modern SPB reissues. Mechanical Prospex (the 6R3x calibers) is the line a Tudor Black Bay buyer cross-shops against.
Sub-lines
- OpenThe modern re-creation of the 1965 62MAS — Seiko’s first dive watch. The SPB143 (silver dial) and SPB147 (blue) carry the 40.5mm case and broad-arrow indices of the period piece, with the 6R35 caliber underneath.
- OpenThe modern re-creation of the 1970 6105 — the cushion-cased dive watch worn by Captain Willard in Apocalypse Now. The SPB151 / SPB153 carry the asymmetric cushion case and 4 o’clock crown of the original, in a 42.7mm case.
- OpenThe modern Alpinist line — descended from the 1959 Laurel Alpinist, with the rotating inner compass bezel and applied cathedral hands. The SPB121 (green dial) is the family reference; SPB117 and SPB119 vary the dial color.
- OpenThe Sumo line — heavy 45mm steel case, the trade nickname for the original SBDC001 (2007). The SPB103 (blue) and SPB101 (black) re-introduced the family in 2019 with the 6R35 caliber and a slimmed case.
- OpenThe Turtle nickname comes from the cushion-cased silhouette of the 1976 6309-7040; revived by Seiko in 2016 with the SRP777 and SRP779. The SRPE93 carries the Save the Ocean Manta Ray colorway with the 4R36 caliber.