Strap for Chronomat 40 GMT Stainless Steel / Green / Rouleaux

The lug width of the Breitling Chronomat 40 GMT A32398101L1A1 is 20mm. This measurement is taken between the two lugs of the case using a digital calliper, with the tips positioned inside the lugs parallel to the case. It is a widely used standard dimension that ensures broad compatibility with aftermarket straps.

The Chronomat 40 GMT pairs exceptionally well with vegetable-tanned calfskin straps for everyday wear, alligator leather for more formal settings, or ballistic nylon NATO straps to maintain the original aviation character. Vulcanised rubber is recommended for those requiring maximum water resistance. The correct width is 20mm with shaped ends to fit the Breitling lugs.

To change the strap on the Chronomat 40 GMT, you will need a spring bar tool or a lug tool to remove the spring bars from the lugs. Apply gentle inward pressure to the ends of the spring bar to disengage it, remove the old strap, and fit the new one with the spring bars correctly seated in the lug holes. It is advisable to have the operation carried out by a watchmaker to avoid scratching the case.

Yes, there is a wide range of aftermarket straps compatible with the Chronomat 40 GMT at 20mm lug width. milanostraps.it offers a selection of handcrafted straps in leather, alligator, calfskin and NATO, specifically constructed for 20mm lugs. It is important to choose straps with ends suited to the curvature of the Breitling case and with correctly sized spring bars (1.5mm standard diameter).

The lifespan of a leather strap depends on the material and conditions of use. A quality vegetable-tanned calfskin strap will typically last 2–4 years with daily wear, developing a personal patina over time. Alligator leather, when properly conditioned, can last over 5 years. To maximise longevity, it is advisable to rotate between at least two straps, avoid prolonged water exposure, and apply a leather conditioner periodically.