Doxa
SUB 300 840.10.021.20— lug 20mm
Doxa SUB 300 840.10.021.20: 20mm strap. Alligator, box calf, shell cordovan and rubber, cut and stitched in Milano. Choose your leather.
Artisanal Note
"This model requires a precise 20mm lug width to preserve the original sartorial balance."
Technical Specifications
Doxa 840.10.021.20The essential strap measurement.
Browse 20mm straps →840.10.021.20
ETA caliber 2824-2 Hours, Minutes, Seconds | Date
The Heritage
Compatible Straps
Selected for the 20mm lug width of the SUB 300
FAQ
What is the lug width of the Doxa SUB 300 840.10.021.20?
The <a href="/pages/termine-glossario/misura-ansa">lug width</a> of the Doxa SUB 300 840.10.021.20 is 20mm. This dimension is standard across all variants of the model. When sourcing a compatible strap, verify the lug width is precisely 20mm: even a half-millimetre deviation causes excessive tension on the case lugs or undesired play. All <a href="https://milanostraps.it/collections/cinturini-orologi-per-misura-ansa-20mm">20mm straps</a> from Milano Straps fit this reference perfectly.
Which strap is most recommended for the Doxa SUB 300?
The Doxa SUB 300 suits three primary options: (1) <a href="/pages/termine-glossario/alligatore">Alligator</a> or vegetable-tanned calf leather for an elegant, vintage-compatible aesthetic that highlights the generous diameter and orange dial; (2) NATO tactical fabric strap in robust textile, honouring the instrument's military heritage; (3) Rubber or FKM strap for intensive diving use, with chemical and temperature resistance. The choice depends on intended use: NATO for terrestrial elegance, rubber for serious diving. Leather demands dry-hand wear to preserve longevity.
How do I change the strap on the Doxa SUB 300 840.10.021.20?
Strap replacement is straightforward. Position the watch case-back toward you and locate the spring bars (anse). Using a dedicated tool, small flathead screwdriver or professional strap-changing tool, gently press one end of the spring bar until it retracts. Once the <a href="/pages/termine-glossario/misura-ansa">lug width</a> slot is free, remove the old strap. Insert the new 20mm strap, align the holes with the spring bars, then apply pressure until you hear or feel a click. Verify security by gently tugging the strap.
Is an aftermarket strap compatible with the Doxa SUB 300 840.10.021.20?
Yes, any strap with <a href="/pages/termine-glossario/misura-ansa">lug width</a> 20mm is compatible. However, verify the strap is manufactured to precise tolerances: insufficient width causes play; excessive width may damage the satin-finished case. Milano Straps manufactures Italian artisanal straps specifically calibrated for 20mm, with meticulous finishing. A <a href="/pages/termine-glossario/deployante">deployante</a> (fold-over clasp) is optional: many prefer stainless-steel accents for visual continuity with the case.
How long does a natural leather strap last on a diving watch?
Durability depends on use environment. A <a href="/pages/termine-glossario/shell-cordovan">shell cordovan</a> or vegetable-tanned calf strap used sparingly (dry wrist, domestic settings) lasts 3–5 years. Regular exposure to salt water, chlorine or prolonged humidity reduces longevity to 1–2 years: aquatic exposure accelerates fibre oxidation and colour loss. For a Doxa SUB 300, FKM rubber or synthetic NATO straps offer superior moisture and saltwater resistance. Milano Straps recommends rotation: wear leather dry-handed in summer; switch to rubber or NATO for diving and water activities; preserve the leather strap for maximum lifespan.