In 1967, to commemorate the company's 100th anniversary, Longines released the Ultra-Chron, a new line of extremely accurate wristwatches. Depending on the watch, the balance system ticked away at a speedy 28,800 or 36,000 beat per hour pace, giving it the ability to run incredibly accurately. (Most vintage watches beat 18,000 times per hour or slightly more.)

The ad campaign's slogan for this award-winning watch was "A New Standard of Time: Guaranteed Accurate to a Minute a Month." In a world before quartz technology, this was an audacious claim. Ultra-Chron watches were the first widely-produced watches to guarantee this accuracy. And it was proved true, even in "real world" testing conditions.

Today's offering showcases this rare officially certified chronometer Ultra Chron. While many Ultra Chrons performed with COSC specs, few were actually submitted for chronometer certification. In many respects, this watch would have been among the best of the best when it came to accuracy in a widely-produced watch at the time.

Adding to it rarity is the fact that it's the only example we''ve ever seen done with this unusual case design.

It is all original and in beautiful condition. Our watchmaker has just performed a partial servicing on it. For the finishing touch we have equipped it with an expensive new crocodile strap with Cartier lining.

Accompanying the watch is its original Longines box.

Photos of the inside are available upon request.

Included with the purchase is a one-year warranty on the movement and its function and a custom printed Connoisseur of Time Certificate of Authenticity.