Seiko Prospex Alpinist SPB121 vs Seiko Prospex 1965 Diver Re-creation SPB143

Side-by-side at a glance. Click a watch above to open the full reference page.

	Seiko SPB121J1	Seiko SPB143J1
Model	Prospex Alpinist SPB121	Prospex 1965 Diver Re-creation SPB143
Caliber	Seiko Cal. 6R35 -- in-house automatic, 28,800bph, 70h PR, 24j; hackable, manual-wind; upgraded from 6R15; used widely in Presage and Prospex lines	Seiko Cal. 6R35 -- in-house automatic, 28,800bph, 70h PR, 24j; hackable, manual-wind; upgraded from 6R15; used widely in Presage and Prospex lines
Case size	39.5mm	40.5mm
Lug-to-lug	46mm	46mm
Years produced	2020–present	2020–present
Brand tier	enthusiast	enthusiast
Era	modern	modern
Movement tier	Unclassified movement	Unclassified movement
Market median (excellent / full-set)	n/a	n/a
Typical range	n/a	n/a
Confidence	low	low
Categories	sport	dive, sport
Editorial	yes	yes
Collector note	best value: In-house Hi-Beat movement with a compass bezel at a price that undercuts the vast majority of Swiss equivalents.	n/a