The IO Annual Calendar was Hysek’s first creation to feature the complication whose name it bears. Now, the manufacture has given the piece a full redesign – and the result is as compelling as it is contemporary.

The piece’s technical highlight is clear from its “Annual Calendar” designation. Indeed, the new-look IO features a calendar than can mark off all the 30 or 31 days in a month flawlessly; only the month of February will require a manual correction. This particular invention was devised just over twenty years ago, in January 1994. It has now been implemented by several other firms in a fairly conventional, standard way – and so Hysek has revisited it, providing a whole new perspective.

Hysek Annual Calendar

The new IO Annual Calendar does not simply display the date, but rather boasts a Large Date display. Behind this subtle difference lies a complex feat of technical prowess, requiring not one date disc, but two. They have to be perfectly synchronised to jump forwards at midnight, and to do so, they require additional energy resources compared to a single date disc. The major challenge is to deliver this calendar movement without taking an excessive toll on the watch’s power reserve. The IO Annual Calendar achieves this, providing over 44 hours of guaranteed autonomy.

The month display benefits from a highly distinctive aesthetic approach. Generally, a central hand is used to indicate the 12 months, since these fall in naturally with the 12 hour markers on the dial, but to preserve the purity and readability of its creation, the manufacture has eschewed this common solution. Instead, Hysek has opted for a disc-based display – thus adding yet another mobile component calling for masterful energy management. Numbered from 1 to 12, the months are displayed in a dedicated window at 8 o’clock, with the current month indicated by an arrow to prevent any possible misunderstanding.

Hysek watch
‍Hysek IO 42 mm Annual Calendar

The entire composition is compellingly audacious, especially its clever play on shapes: a circular dial; arrowhead hands; a large, rectangular double window date display; and months displayed through a comma-shaped window. The sun-brushed dial also features a circular guilloché seconds counter. Very few firms are capable of producing a piece comprising so many different styles that maintains such an air of complete wholeness.

Last but not least, Hysek collectors will note the hours display, in which only the manufacture’s hallmark figures of 1, 5, 7, and 11 are used. At twelve o’clock, the Hysek “H” takes the place of the figure 12, and is also to be found on the crown.

The assembly is housed in a 42-millimetre case complete with the IO collection’s characteristic lugs, each bearing three ‘clawmarks’. Hysek is presently offering two steel variations of the piece, one with a grey dial and black alligator strap, the other with a blue dial and blue alligator strap, each with a fold-over buckle. The Swiss Made calibre, packed with 193 components, is visible through a sapphire crystal caseback.



Automatic Mechanical

Annual Calendar and Grande Date

Month Counter at 8 o’clock

Small Seconds at 5 o’clock

Côtes de Genève decoration

193 components

30 jewels

Autonomy 44h

Frequency 28’800 VpH


Dimensions : Ø42mm x E12mm

Round shape


Water resistance 50m

Sapphire crystal with anti-reflection

Screwed crown

Silvered or blue sun-brushed dial

Hysek fold-over buckle

Bracelet in leather or in steel