SUB 300 Professional

Ref. 821.10.351.10

Case diameter: 42.5 mm; Manufacturer spec
Lug-to-lug: 45 mm; Manufacturer spec
Thickness: 13.4 mm; Manufacturer spec
Lug width: 20 mm; Manufacturer spec

Retail price $2,890 (US, Oct 2026)

Your wristIdeal fit

Wrist flat: 55.1 mmLug-to-lug: 45 mm

How the SUB 300 Professional wears

Its lugs add only 2.5 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 13.4 mm thick it is thicker than 70% 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 300 Professional fit your wrist?

With a 45 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: 821.10.351.10
Collection: SUB 300
Status: In production
Case material: stainless steel
Crystal: sapphire
Water resistance: 300 m
Bezel: unidirectional with patented no-decompression depth/dive-time scale (meters)
Dial: orange (Professional)
Strap / bracelet: 'Beads of Rice' steel bracelet or FKM rubber strap, folding clasp with wetsuit extension
Style: Dive

Movement

Movement details coming soon.

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 300 Professional.

Sources

doxawatches.com/products/sub-300-professional