Strap for Perpetual Calendar Chronograph 3990 Platinum / Slate

The lug width of the Patek Philippe 3990P-XX1 is 20 millimetres. This measurement represents the classical standard for wrist watches between 36 and 38 millimetres, ensuring proportional balance between case and strap. To verify it, measure the internal space between the two upper case lugs, not between the pins. A correctly sized strap will seat perfectly on the platinum case without lateral movement.

For a 36mm platinum case, the strap becomes a material extension of the timepiece. Nile alligator is the most balanced choice: semi-flexible leather with pronounced grain that captures light diffusely. Shell cordovan offers tactile hardness and develops golden patinas that contrast beautifully with the case. Vegetable-tanned calf provides compact fibre and develops deep patinas over time. For practical wear, quality allogeneic rubber remains a reliable option without aesthetic compromise.

Strap replacement is accomplished through the lug attachment pins. Obtain a pin removal tool (stylus or dedicated implement) and a small lever. Support the watch on a soft surface. Position the stylus beneath the pin from the side, apply gentle outward pressure until release. Extract the pin and repeat on the other side. Insert the pins into the new 20mm strap, align the lugs to the case and press the pins gently into place. Verify that the strap sits symmetrically without lateral play.

Yes. Any strap with a 20mm lug width is compatible with the 3990P-XX1, provided the attachment pins are of standard dimensions. Milanostraps.it offers a curated collection of 20mm straps in alligator, shell cordovan, calf and rubber, crafted artisanally and certified for dimensional precision. Compatibility is guaranteed, as is construction quality. Partnership with Casati Milano allows verification of your chosen strap in the atelier and monitoring of every manufacturing phase.

Durability depends on leather type and usage pattern. Nile alligator and vegetable-tanned calf typically last 3-5 years with moderate daily wear, developing patinas that increase aesthetic value. Shell cordovan, being denser, reaches 5-7 years. Quality rubber lasts 4-6 years. Wear is natural: the strap softens, patina deepens, lug attachments loosen slightly. Casati Milano provides 18-month warranty on production defects and recommends annual maintenance to extend useful life and preserve the strap in optimal condition.