Strap for Perpetual Calendar Chronograph 3970G Arabic

The Patek Philippe 3970G_Arabic is equipped with a lug width of 20 mm. This measurement represents Patek Philippe's standard for the perpetual chronograph in the Grand Complications collection. The measurement is taken between the horizontal lugs (the metal protrusions on the case flanks) upon which the strap rests. To verify this measurement, position a digital calliper perpendicularly between the two lugs: the value must be precisely 20 mm. This accuracy is essential to ensure that the strap fits perfectly to the lugs without play or excessive tension.

For the 3970G_Arabic, alligator represents the reference choice: its parallel grain and controlled lustre naturally dialogue with the white gold case and the typographic seriousness of the Arabic numerals. Shell cordovan offers a more structured alternative, with superior tactile density and a patina that develops over time. For a minimalist approach, vegetable-tanned calf creates an almost ascetic surface that does not distract from the perpetual calendar movement. A silk or natural cotton NATO fabric also permits contemporary reinterpretation without betraying the formal identity of the timepiece. The choice depends on occasion of use and personal sensitivity towards colour and texture.

To change the strap on a timepiece with a 20 mm lug width, you require a specific tool called a spring bar tool (or lug remover). Position the watch on an anti-scratch pad and identify the two horizontal lugs on the case flanks. Insert the flat end of the spring bar tool into the space between the lug and the strap, then apply lateral pressure to compress the lug's internal spring. The strap will release. Repeat the operation on the other side. To install the new strap, align the holes at the same height as the lugs and push until the spring clicks into position. This is a delicate procedure: should you prefer, contact a specialised service centre or Casati Milano, which offers this operation by appointment.

Yes, an aftermarket strap is absolutely compatible with the 3970G_Arabic, provided that the lug width is precisely 20 mm and that the construction quality is appropriate for a timepiece of this prestige. A third-party brand strap — such as those offered by Casati Milano or by specialised suppliers — permits you to express personal character and to modulate the watch's use according to occasion. What matters is choosing conical materials (full grain leather, cordovan, genuine alligator) and impeccable stitching, so that the strap does not wear prematurely. A reliable aftermarket strap amplifies styling possibilities whilst maintaining full functionality and wearing security.

The lifespan of a leather strap depends on the material, the tanning method employed, and the intensity of use. Superior-quality alligator, worn occasionally, can last 5–7 years without significant wear. Shell cordovan — owing to its fibrous structure — retains functionality for 8–10 years, although the patina changes considerably. A vegetable-tanned calf, being more delicate, typically requires 3–5 years of use before exhibiting signs of failure (generally the lugs begin to loosen). Exposure to direct sunlight, humidity, and perspiration accelerates ageing. To extend the strap's life, keep the watch in dry environments and occasionally apply a protective cream to the leather. Casati Milano offers an 18-month warranty on manufacturing defects, thus covering the critical initial period.