Strap for SUB 300T Professional

The lug width of the Doxa SUB 300 840.10.351.21 is 20mm. This measurement represents the distance between the lugs on the watch case that hold the strap in place and is essential for ensuring compatibility with aftermarket straps. When measured correctly, it allows the use of a wide range of straps without lateral play or structural misalignment.

The choice depends on the intended use: for formal occasions, an alligator strap with vegetable tanning conveys elegance whilst maintaining the model's authenticity; for daily marine use, a NATO strap in woven nylon offers robustness and quick drying; for deep diving, vulcanised FKM rubber ensures thermal stability and chemical resistance. Each material represents a conscious compromise between aesthetics and practicality.

Strap changing requires a dedicated tool (spring bar tool) to remove the elastic pins that connect the strap to the case. Position the watch on a stable surface, insert the flat tip of the tool into the access hole of the lower lug, apply gentle pressure to release the pin, then extract it. Repeat the operation on the upper lug. Insertion of the new strap follows in reverse sequence, ensuring that the pins click into position with an audible confirmation.

Any strap with a 20mm lug width is compatible with the Doxa SUB 300. This includes leather straps (alligator, calf, shell cordovan with vegetable or chromium tanning), NATO straps in woven nylon, vulcanised FKM rubber straps and hybrid leather-rubber straps. Compatibility is guaranteed provided the lug width does not deviate from the 20mm specific to this model.

The lifespan of a leather strap depends on frequency of use, exposure to moisture and the construction quality of the material. An alligator or shell cordovan strap with vegetable tanning, used daily in a non-maritime environment, maintains structural integrity for 3-5 years; a chromium-tanned calf strap offers similar durability with less initial patina development. Regular exposure to seawater reduces longevity to 12-18 months, so vulcanised FKM rubber straps are recommended for frequent diving and seasonal changes to preserve the material.