Seaforth IV

Case diameter: 41 mm; Manufacturer spec
Lug-to-lug: 46.5 mm; Manufacturer spec
Thickness: 12.4 mm; Manufacturer spec
Lug width: 20 mm; Manufacturer spec

Retail price $765 (US, Oct 2026)

Your wristIdeal fit

Wrist flat: 55.1 mmLug-to-lug: 46.5 mm

How the Seaforth IV wears

Its lugs add only 5.5 mm to the 41 mm case, against 7.1 mm typical across the almanac, so it wears smaller than its diameter suggests.

On our fit model it sits best on wrists from 6.5" to 7.75" (16.5–19.7 cm); below 6.5" the lugs start to reach the edge of the wrist.

At 12.4 mm thick it is slimmer than 73% of the 79 other dive watches we've measured, so it slides under a cuff more easily than most.

Its 20 mm lug width is one of the most common strap sizes; 104 other watches here share it, so aftermarket straps are easy to find.

Will the Seaforth IV fit your wrist?

With a 46.5 mm lug-to-lug, here is how it wears across common wrist sizes. We estimate the flat top of each wrist from its circumference; measure yours for a closer answer in the fit finder.

Wrist	Flat width (est.)	Fit
6"	47.2 mm	Lugs overhang
6.5"	51.2 mm	Ideal fit
7"	55.1 mm	Ideal fit
7.5"	59.1 mm	Ideal fit
8"	63 mm	Wears small

Specifications

Reference: Seaforth IV
Collection: Seaforth
Status: In production
Case material: titanium
Crystal: sapphire
Water resistance: 200 m
Bezel: unidirectional 120-click with sapphire insert (also fixed-bezel version)
Dial: sunburst blue, plum, grey; pastel blue, yellow, pink
Strap / bracelet: titanium bracelet with steel clasp, or rubber strap
Style: Dive

Movement

Caliber: Sellita Sellita SW200-2
Type: automatic
Power reserve: 65 hours

Takes 20 mm straps. See other 20 mm watches and straps.

Watches that wear the same size

Other watches within 1.5 mm of its lug-to-lug.

Same 20 mm lug width

All 20 mm watches

These take the same straps as the Seaforth IV.

Sources

halioswatches.com/products/seaforth-iv-gs