They have the same mesmerizing fascination as a deck of cards being riffled-shuffled in the hands of a deft casino blackjack dealer, and that same fascination is now part of an amazing watch –the new Epic "SF 24" timepiece from Jacob & Co.. 

Jacob & Co. has taken the same magic found in split-flap displays –also often called "Solari boards" after the Italian firm, Solari di Undine, which manufactures them –and transported it into a wristwatch. The SF 24 –"SF" of course stands for "Split Flap" --combines a dial which shows the time in a conventional fashion with a split flap display in a roller housing at the top of the dial, which shows the time in a second time zone. Two split flap systems show, on the left, the name of the reference city, and on the right, the hour for the city shown. The "24" refers to the 24 cities from which the owner can choose, corresponding to the 24 major time-zones with one hour offsets from Greenwich Mean Time.

The entrancing mechanical complexity of the split flap display is a breath of horological fresh air; the system has never before been used in a wristwatch and it lends an air of both innovation and cosmopolitan, jet-setter glamour to this highly unusual timepiece. Augmenting the dual split-flap display is the rich complexity of the transparent dial, which reveals parts of the movement and puts even more in the spotlight the romance of machinery expressed by the SF 24. 

The shape is a sleek and streamlined housing for the complication, both refreshingly different and reassuringly logical in form and execution, with a large and easy to operate crown at 4:00 balanced by the pusher for adjusting the split time display, set into the side of the cylinder that houses it. It's all shown off by a complex, two-part sapphire crystal that allows each of the two displays to be revealed with stunning clarity.

Despite its remarkably innovative design, the SF 24 –the only dual time zone watch of its kind –is eminently wearable at 45mm overall, and houses a movement created exclusively for Jacob & Co. –the mechanical self-winding Concepto based Caliber 2220, with the exclusive GMT-SF24 module developed by Studio7h38. The self-winding movement has a 40 hour power reserve, and the SF 24 is offered in white gold, rose gold, or high-tech Grade 5 titanium. 

With the SF 24, Jacob & Co. continues its proud tradition of creating multi-time zone timepieces for the world's most demanding –and discerning –travellers.