Strap for SUB 300T Aquamarine

The lug width of the Doxa SUB 300 840.10.241.25 is 20 mm. This measurement, also known as strap width, determines compatibility with aftermarket straps. To verify it precisely, use a digital calliper and measure the distance between the centres of the two internal lugs on the case. The Doxa warranty documentation often lists this specification.

For the SUB 300, we recommend three categories: black or dark brown alligator for classic diver elegance, vegetable-tanned calf for balancing modernity and tradition, or NATO fabric or FKM rubber strap for aquatic performance. Your choice depends on intended use and desired aesthetic tone. All straps must feature a 20 mm lug width.

Remove the current strap by extracting the spring bars—small cylinders that connect the strap to the case lugs. Use a dedicated tool (spring bar tool) and proceed gently to avoid scratches. Once both bars are removed, the strap releases freely. Insert the new strap of the same size (20 mm), aligning the holes, and reinsert the bars in reverse. Verify that the strap is centred and does not shift laterally.

Yes, any strap with a 20 mm lug width is compatible with the SUB 300 840.10.241.25, provided the spring bars are of identical diameter (typically 1.5 mm). Quality artisanal straps often feature adjustable or replaceable bars. Before purchase, confirm that the seller specifies 20 mm compatibility and that the strap is supplied with correct bars.

The lifespan of a leather strap varies according to use, climate and maintenance. A quality alligator strap, worn daily in temperate conditions, lasts approximately 3–5 years. Leather fears excessive humidity and repeated contact with salt water. If your SUB 300 is destined for frequent immersion, a rubber or NATO strap is more appropriate. Regular maintenance (gentle cleaning, storage in a dry location) significantly extends strap life.