This is a wristshot of a very rare Patek Philippe I saw at SIHH last week, a Ref. 5550P. Originally launched at Baselworld 2011, the watches are finally reaching collectors now.

The Patek Philippe Advanced Research 5550P is the fourth in a series of watches equipped with Patek’s advanced silicium components. Unlike the annual calendars from the first three models in the series, the 5550P uses a modified caliber 240QP Perpetual movement, and for the first time, it includes Patek’s complete system of silicium components, referred to as “Oscillomax”, it consists of a Pulsomax escape wheel and pallet fork, GyromaxSi balance wheel with adjustable gold weights, and the Spiromax hairspring.

The thin polished platinum case measures 37.2 mm in diameter with a fixed bezel, vertically brushed silver dial with gold markers and hands. Sapphire crystal case back. Visually, watching the Oscillmax system through the case back, specifically the Gyromax balance wheel, is mesmerizing.

Silicium components are much lighter than traditional steel components, and they can react faster. When used in watchmaking this can greatly improves the ability for the watch to transfer of power between components. This leads to improved efficiency, better timekeeping and less friction, negating the need for lubrication. Furthermore, the watchmakers at Patek used the efficiency to boost the power reserve to 70-hours from 48.

Only 300 were made in a limited edition.

Complete Patek Philippe “Oscillomax” system

GyromaxSi Balance wheel

Pulsomax escapement wheel and pallet

Spiromax hairpsring