SUB 300T Professional

Ref. 840.10.351.10

Case diameter: 42.5 mm; Manufacturer spec
Lug-to-lug: 44.5 mm; Manufacturer spec
Thickness: 13.7 mm; Manufacturer spec
Lug width: 20 mm; Manufacturer spec

Retail price $2,190 (US, Oct 2026)

Your wristIdeal fit

Wrist flat: 55.1 mmLug-to-lug: 44.5 mm

How the SUB 300T Professional wears

Its lugs add only 2 mm to the 42.5 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 6.25" to 7.5" (15.9–19.1 cm); below 6.25" the lugs start to reach the edge of the wrist.

At 13.7 mm thick it is thicker than 77% of the 79 other dive watches we've measured, so expect it to sit tall on the wrist.

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 SUB 300T Professional fit your wrist?

With a 44.5 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	Snug, lugs near the edge
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: 840.10.351.10
Collection: SUB 300T
Status: In production
Case material: 316L stainless steel
Crystal: sapphire, anti-reflective
Water resistance: 1200 m
Bezel: unidirectional, no-decompression dive table (feet)
Dial: orange
Strap / bracelet: beads-of-rice steel bracelet with ratcheting extension
Style: Dive

Movement

Caliber: ETA 2824-2
Type: automatic
Power reserve: 38 hours
Frequency: 28,800 vph (4 Hz)

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 SUB 300T Professional.