No one I know is considered more renowned for their work of the Perpetual Calendar complication than Ludwig Oechslin. Most perpetual calendars utilize numerous delicate levers and springs which are usually very sensitive to shock and long term use. Recognizing this, Mr. Oeschlin designed a perpetual with a far more practical approach. Utilizing gears instead of levers and springs, he was able to create a clever and reliable movement adding just 9 additional parts. All setting is accomplished through the crown and can be adjusted both forwards and backwards without any fear of damaging the mechanism.

Below is taken from the Ochs und Junior website:

Reading the functions
Date
The 30+1 holes around the perimeter of the dial display the date. The 10 minute markers serve as reference points. For example: the marker indicating 30 minutes also shows the 15th day of the month (30÷2=15). These 5 day markers allow for the date to be read at a glance and after a short time, you can recognize the date intuitively. The first picture of this listing indicates it is the 11th.
Month
The 4 perforations in the month disk indicate the month. When the outermost perforation points to 1 o’clock, it is January. When the outermost perforation points to 2 o’clock, it is February. The month disk rotates clockwise. The first picture of this listing indicates it is the 7th month, July.
Leap year
The 4 perforations in the month disk also show whether it is a leap year or a common year. When the outermost dot is orange, it is a leap year (366 days). When it is dark, it is a common year (365 days). The leap year disk rotates clockwise beneath the month disc. The first picture of this listing indicates it is year 3 of 4. Next will be Leap Year.
Power reserve
The small circle beneath 12 o’clock is the power reserve indicator. Full power (60 hours) is when the dot is beneath the rightmost 12 o’clock marker. Empty is when the dot is beneath the leftmost 12 o’clock marker. The disk rotates counterclockwise. The first picture of this listing indicates the power reserve is empty.
Hour and minute
The exact minute can be read using the date holes, which are spaced at 2 minute intervals. Holes mark even minutes and gaps odd minutes.
Second
Just above the 6 o’clock marker is a seconds disk with a milled eccentric dot. This rotating disk indicates that the watch is running.
Control dot
The control dot is located between 1 and 2 o’clock. Together with the time, the control dot shows when it is okay to adjust the date.
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The Grade 5 titanium case is lightweight (76.4g including strap) and is fit with a curved caseback to perfectly hug your wrist. When you factor this in with the tiny lugs you have a watch that wears like a 40mm. The case is in excellent condition and measures 42mm in diameter and 42mm lug-to-lug! 12.5mm thickness.

The watch was delivered new February 2018. Current retail 23,320.00 CHF Asking $16,500. CA residents subject to sales tax.
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www.horologybythesea.com