Patek Philippe 10 Days Power Reserve

The 10 Days Power Reserve line consists of rectangular hand-wound watches with a ten-day power reserve. The Swiss manufacture Patek Philippe released them in a limited edition to mark the start of the third millennium. At their heart is the rectangular Patek Philippe calibre 28-20/220 PS IRM, developed specifically for the year 2000. Its two mainspring barrels are coupled in series and provide a power reserve of 240 hours.

The crystal and caseback are sapphire, and the calibre is visible through the back. The 10 Day Limited Edition reference 5100J has a silvered dial with applied yellow gold Arabic numerals and markers, and two counters: a power reserve indicator and small seconds. It is a men's wristwatch on a leather strap, intended for formal dress.

Within the line, the choice is first about the case metal; the 5100J is in yellow gold. For pre-owned pieces, condition, signs of polishing and completeness of set also matter. For similarly shaped Patek Philippe models, see the Gondolo collection.