The Seiko Prospex HBC005J1 is the premium model in Seiko's second wave of 145th Anniversary Prospex limited editions — the 1965 Heritage Diver in Seiko Blue, limited to 4,000 pieces worldwide. Built on the 1965 Heritage platform that traces its design DNA directly to the 62MAS — Japan's first diver's watch, produced in 1965 — the HBC005J1 takes the iconic compact 40mm case and applies the 145th Anniversary Seiko Blue treatment: a blue aluminium unidirectional rotating bezel, a blue seconds hand, and a silver-white dial that creates the clean, cool, formally modern aesthetic that defines the entire 145th Anniversary series.

The specification is where the HBC005J1 separates itself decisively from the HBB001K1 sibling. The 6R55 calibre delivers +25/-15 seconds per day accuracy and a 72-hour power reserve. The curved sapphire crystal with anti-reflective coating replaces Hardlex with premium optical clarity. Water resistance is rated Diver's 300M. The three-fold clasp with secure lock, push-button release, and slide adjuster completes a full professional diver's specification.

Movement
Caliber Number: 6R55
Movement Type: Automatic with manual winding
Precision: +25 to -15 seconds per day
Power reserve: Approx. 72 hours(3 days)
Jewels: 24

Functions
Stop second hand function

Case/Band
Case Material: Stainless steel
Case Size
Thickness:13.0mm
Diameter:40.0mm
Lug-to-lug:46.4mm
Crystal: Curved sapphire crystal
Crystal Coating: Anti-reflective coating on inner surface
LumiBrite on hands, index(es) and bezel
Three-fold clasp with secure lock & push button release, solid & slide adjuster
Distance between lugs: 20mm

Features
LIMITED EDITION on the case back
Unidirectional rotating bezel
Screw-down crown
Screw case back

Other Details
Water Resistance: 300m / 1000ft diver's
Magnetic Resistance: 4,800 A/m